Sister-brother Incest: Data from Anonymous Computer Assisted Self Interviews

Abstract

Retrospective data were entered anonymously by 1,178 adult men using computer-assisted self-interview. Twenty-seven were victims of sister-brother incest (SBI), 119 were victims of child sexual abuse by an adult female (CSA-AF) before 18 years of age, 1,032 were controls. SBI was often the first sexual experience for the victim. Our findings were consistent with other reports of early and persistent hyper-eroticization of incest victims. SBI increased the likelihood of engaging in behaviors as an adult consistent with a co-existing or primary male-male sexual orientation, and SBI and CSA-AF had deleterious impacts on adult men's sexual adjustment with their adult partners.

Meiselman (1979, pp. 294–298) found eight cases of brother-sister incest described by sisters (BSI) and three cases sister-brother incest described by brothers (SBI) in her clinical sample. The three SBI victims Meiselman (1979) described had all been harmed by the SBI, but the victims described in two of the three cases also had been victims of incest perpetrated by other family members (the mother in one case and a brother in the other case). Over the subsequent 32 years, there have been at least 20 studies focused on the effects of BSI on the sisters (see Stroebel, O’Keefe, Beard et al., 2013), but there have been no controlled studies focused on the effect of SBI on the brothers. Despite a computerized search in October 2013 of the Medline, PsychINFO, and PsychARTICLES databases using Academic Search Premier for the term “incest” in the abstract, the papers related to SBI cited in this paper were the only ones that provided substantive background for our present study. Due to the dearth of data in the more recent literature on SBI, we were forced to turn to the older literature to find the original research with the most useful data about SBI.

In general, child sexual abuse (CSA) by female perpetrators on male victims has remained far less studied than has CSA by male perpetrators for reasons that include a number of untested assumptions: that males are protected by not being able to get erections when their participation is coerced, that males are not harmed even when their participation is coerced, that minor males are not harmed by participating in sex with adult females, that males are not harmed when they can be viewed as the perpetrator, and that the males are not harmed when they believe that their participation is voluntary (Sarrel & Masters, 1982; see Deering & Mellor, 2010 and Grayston & De Luca, 1999 for reviews).

Finkelhor (1979) defined incest as any sexual behavior among relatives, and this was the definition that we chose to use in our present study (p. 84). Some investigators have attempted to differentiate “normal” sexual experimentation among consenting siblings from CSA using one or more criteria such as whether or not there was an age difference, whether or not coercion was involved, whether or not the participant was able to give consent, or even whether or not it was heterosexual experimentation (e.g., Bank & Kahn, 1982; Greenwald & Leitenberg, 1989; Russell, 1986; Weinberg, 1955; Wiehe, 1990), but such approaches assumed that some sexual experimentation among siblings is normal and harmless and excluded the part of the sample that would potentially have permitted testing the assumption. Some investigators obfuscated SBI effects on male victims by analyzing male SBI victims and female brother-sister incest (BSI) victims as a single group or intermingling descriptions of cases of SBI with BSI, mother-son incest (MSI), or mother-daughter incest (MDI). The few studies that have reported any data on SBI have reported only a small number cases of SBI (i.e., three cases, Caffaro & Conn-Caffaro, 2005; three cases, Carlson, Maciol, & Schneider, 2006; one case, Deering & Mellor, 2011; three cases, Meiselman, 1979, pp. 294–298; 13 cases, Nelson, 1981; three cases, Sarrel & Masters, 1982), but only two of these sources provided actual outcomes for pure SBI cases without comingling effects with other types of incest (i.e., 1 case, Meiselman, 1979, pp. 295–298; 3 cases, Sarrel & Masters, 1982). Both sources selected for cases with adverse outcomes by using individuals in psychological treatment for sexual or emotional problems as study participants. Some authors have focused on the brother as sexual offender without providing data on the effect on the brother (i.e., Adler & Schutz, 1995). Other reports described intermingled effects reported by male and female victims of female perpetrators (i.e,, one SBI case, Deering & Mellor, 2011; one SBI case, Denov, 2004; Wiehe, 1990). The few case reports in the literature were not accompanied by data on suitable controls, and the numbers of cases were too small to allow meaningful statistical analysis (i.e., one case, Meiselman, 1979, pp. 295–298; three cases, Sarrel & Masters, 1982).

Sarrel and Masters (1982) and Johnson and Shrier (1987) reported sexual dysfunction in small numbers of men in their study on men who had been victims of Child Sexual Abuse by an Adult Female (CSA-AF). However, Condy, Templer, Brown, and Veaco (1987) in non-clinical prison and college student samples, respectively, found the majority of CSA-AF victims said that their CSA-AF experience had either no effect or a good effect on their adult sexual function. Condy et al. (1987) also found that the majority of men in non-clinical samples evaluated incestuous sexual contacts with adult females as negative at the time that they occurred and as ultimately having a negative effect on their adult sexuality. The 17 cases of MSI in clinic-referred men reported by Kelly, Wood, Gonzalez, MacDonald, and Waterman (2002) suggested that MSI victims were more harmed by the MSI when the victims responded positively to the abuse, a finding that called into question three implicit, unproven, and untested assumptions regarding effects of CSA on male victims: (a) that harm can be assessed accurately by the victims themselves; (b) that voluntary participation is less harmful than coerced participation; and (c) that a positive initial response is associated with less harm than a negative initial response.

There is growing evidence that all types of incest that start early in the victims’ lives tend to result in early hyper-eroticization of the victims that persists into adulthood (e.g., Beard et al., 2013; Stroebel et al., 2012; Stroebel, O’Keefe, Beard et al., 2013; Stroebel, O’Keefe, Griffee et al., 2013; Yates, 1982), and the mechanism behind this effect appears to be a type of early learning directly related to sexual functioning called sexual imprinting (Beard et al., 2013; for a review of animal studies on sexual imprinting see Irwin & Price, 1999) working in concert with Pavlovian conditioning and operant conditioning (Beard et al., 2013; Bickham et al., 2007). Furthermore, sexual imprinting working in concert with Pavlovian conditioning and operant conditioning is the mechanism that explains the powerful tendency of same-sex sibling incest or non-incestuous early experiences with same-sex partners to produce permanent adult same-sex or bisexual orientations in the victims (Beard et al., 2013; Bickham et al., 2007; Hoffman, 2012; Pfaus et al., 2012; Robinett, 2012; Stroebel, O’Keefe, Griffee et al., 2013).

Very early and life-long eroticization, shaming, emotional cut-offs from sibling incest-partners, cognitive dissonance (Beard et al, 2013; Caffaro & Conn-Caffaro, 1998; Festinger, 1957; Stroebel et al., 2012; Stroebel, O’Keefe, Griffee et al., 2013), and conditioning acting in concert with sexual imprinting (Beard et al., 2013; Bickham et al., 2007; O’Keefe et al., 2009; Stroebel et al., 2010; Stroebel, O’Keefe, Griffee et al., 2013) are all important mechanisms that could cause harm as a result of participating in sexual experiences in childhood or adolescence that would not be readily apparent to the victims, themselves, and which could occur whether or not participation was voluntary and whether or not the participant's initial response was positive or negative.

The present study analyzed data from all the victims of SBI among the 1,178 male participants (without regard to whether their participation was voluntary or coerced and without regard to the direction or size of the age differential between the brother and the sister because all 27 cases fit our definition of SBI incest and because Kelly et al. [2002] showed that positive response to MSI did not preclude harm). In the present research, we compared the data from the SBI victims to the data from two appropriate control groups: (a) victims of child sexual abuse by a female adult other than a sister (CSA-AF) and (b) controls who were not victims of SBI or CSA-AF in an experimental design analogous to both the brother-brother incest (BBI) study of Beard et al. (2013) and the BSI study of Stroebel, O’Keefe, Beard et al. (2013). In order to allow us to maintain and convey a level of concern for the welfare of the male participants similar and parallel to that maintained and expressed for female victims of male perpetrators, the male participants in groups (a) and (b) have been systematically referred to as victims and the females sexual partners as perpetrators in this article, whether or not the male respondents had characterized the behaviors that they engaged in with the female partners as voluntary or coerced. Furthermore, the first five of the empirically based hypotheses that we tested statistically and the data variables from the male participants were similar and analogous to those already investigated by Stroebel, O’Keefe, Beard et al. (2013) who used data on BSI from female participants. The last hypothesis was added to test whether the finding of Kelly et al. (2002), that positive response to MSI did not preclude harm, would be repeatable in the data from BSI victims. The items used for the present study were included as part of a larger anonymous computerized “cradle to the grave” study of human sexuality.

Our hypotheses were as follows: (a) Child sexual abuse by female perpetrators has global adverse effects on male victims; (b) Child sexual abuse perpetrated by a sister starts earlier than CSA-AF; (c) SBI is often the first sexual experience for the brother; (d) Child sexual abuse by female perpetrators has a deleterious impact on an adult man's sexual adjustment with his adult partners; (e) The effects on the victims of SBI differ from those of CSA-AF; and (f) SBI can have adverse effects on the brother-victim when his participation is voluntary and also when his participation is coerced.

METHOD

Participants

A total of 1,178 male participants completed the interview. The median age was 21 years (M = 26.5, SD = 12.0, range: 18–86 years). The education level of the participants was as follows: 6.1% high school only, 70.3% some college, 14.5% bachelor’s degree, 4.9% master's degree, and 4.2% doctoral degrees. All participants were over the age of 18 and gave informed consent using forms approved by the relevant institutional review board. The participants were recruited from a population consisting mainly of undergraduate and graduate college students from six mid-sized, mid-Atlantic college campuses using bulletin board postings and announcements in classes. To obtain a wider base and to increase age, education, and life-experience diversity, we also recruited university faculty and staff and individuals from the same general population of the mid-Atlantic United States who had already completed their education. We included all individuals who were 18 years old or older who were willing to participate in the study after being provided with information about the risks and benefits of the study. We received approval to begin data collection in 2002 on the two Marshall University campuses and at the Charleston Area Medical Center/West Virginia University Charleston campus. In 2004 we received approval to begin data collection at the West Virginia University Morgantown campus. In 2007 we received permission to begin data collection on the West Virginia State University campus in Institute, WV, and in 2009 we received permission to begin data collection on the Concord University campus in Athens, West Virginia. The announcement processes were slightly different on each of the campuses because we relied on the individual professors to make announcements to their classes. In some cases, the investigators were invited into classes to make the announcements. In order to increase the number of sexual minority individuals who participated in the study we attended area “Pride” parades and gay and lesbian picnics and worked with gay and lesbian churches and other organizations friendly to gays and lesbians. Members of these groups were also invited to participate. Whenever individuals agreed to participate, we encouraged them to bring along friends to participate or to encourage their friends to participate at a later time (snowball recruiting). All participants were unpaid, but many of the students received credit from their professors in psychology, social work, and criminal justice courses. Moreover, all participants were volunteers.

Measures

The CASI program (S-SAPE1, ©S-SAPE, LLC, 2002, P.O. Box 11081, Charleston, WV 25339), the scale validation, the items (except for correction from male to female wording), and item numbering used for the present study have been described in numerous studies (Beard et al., 2013; Stroebel et al., 2012; Stroebel, O’Keefe, Beard et al., 2013; see Haning et al., 2007 for a full description of the S-SAPE1 sexual behavior screen used to obtain detailed quantitative data about a variety of sexual behaviors and Beard et al., 2013 and Stroebel et al., 2012 for validation of the following scales as administered by the S-SAPE1 CASI program). See Appendix A and Appendix B for items used in the present research. Additional validation pertinent to the present research based on data from these 1,178 participants has been provided in Beard et al. (2013).

Items related to incest were presented interspersed among similar items not related to incest. Variables describing behaviors that constituted CSA by an adult female were constructed by the computer program to insure that they were worded similarly to those previously presented that described the same behaviors with male partners (a) whose age was within 4 years of the participant's and (b) whose age was more than 4 years older than the participant's but under age 18.

Depression

The Center for Epidemiologic Studies Depression Scale (CES-D; Radloff, 1977) was used to assess depression. The measure consists of 20 items, measured on a Likert scale ranging from 0 (rarely or none of the time [less than 1 day]) to 5 (most or all of the time [5–7 days]). Internal consistency of the CES-D in the present sample was Cronbach's α = .882.

Intimacy

The Intimacy Scale (Walker & Thompson, 1983) hereafter referred to as the Intimacy-1 scale, was used to assess intimacy. The measure consists of 17 items, measured on a Likert scale ranging from 0 (never) to 4 (always). Internal consistency of the Intimacy-1 scale in the present sample was Cronbach's α = .964.

Intimacy as expressed in communication about sexual issues was assessed using the Sexual Partner Intimacy Scale (Haning et al., 2007), hereafter referred to as the Intimacy-2 scale. The measure consists of 9 items, measured on a dichotomous scale. Internal consistency of the Intimacy-2 scale in the present sample was Kuder-Richardsonformula20 α = .588.

Sexual Satisfaction

The Sexual Relationship Index scale used in prior publications contained 27 items (SRI-27, Haning, 2005; Haning et al., 2007). In the present work, the SRI-27scale has been augmented by inclusion of two additional items (assessing whether the participant believes that his partner wants too much sex or dwells excessively on sex) to produce the SRI-29 scale. The correlation of the SRI-29 with the SRI-27 was r = .995 (see Appendix B for the items and the composition of the SRI-27, the SRI-29, and the three subscales of the SRI-29). The SRI-29 (hereafter referred to as the Sexual Satisfaction scale) was used to assess sexual satisfaction. The measure consists of 29 items (15 of which were reverse scored), measured on a Likert scale ranging from 0 (less than 10% of the time) to 4 (more than 90% of the time) with a possible total score range of 0 to 116. Internal consistency of the Sexual Satisfaction scale in the present sample was Cronbach's α = .907 for the 29-item scale (versus α = .918 for the 27-item scale). Factor analysis of the data from the present 1,178 participants with a scree plot and Varimax rotation showed that the 29-item scale contained three subscales: the 14-item Sex-positive and Partner Affirming Statements sub-scale with α = .961, the 7-item Sex-negative Statements about Sex with the Partner sub-scale (which includes the two additional items) with α = .675, and the 8-item Sex-positive Complaints about Sex with Partner sub-scale with α = .778.

Conflict

The Conflict scale (Haning et al., 2007) was used to assess conflict between sexual partners. The measure consists of 9 items, measured on a dichotomous scale. Internal consistency of the conflict scale in the present sample was Kuder-Richardson formula 20 α = .713).

The sum of the individual item scores was used as the composite score for each of the measures. Construct validity of the first five measures above was demonstrated by the statistically significant correlations among the scales which were consistent with theory (Haning et al., 2007; see Table 2).

Table 2 Scores on Ten Psychological Scales Analyzed Using Two-way ANOVA

	Sister-brother incest n = 27	CSA-AF n = 119	Controls n = 1032
	Mdn^1, mean ± SD	Mdn^1, mean ± SD	Mdn^1, mean ± SD
CES-D depression scale	12.6 ± 11.6	12.0 ± 8.3	11.3 ± 8.1
Intimacy-1 scale	45.4 ± 15.1	47.7 ± 15.5	47.2 ± 15.6
Intimacy-2 sexual communication scale^2	4, 3.9 ± 2.4	6, 5.2 ± 1.7	5, 4.9 ± 1.7
Conflicts scale^2	3, 3.4 ± 2.5^c*	2, 2.5 ± 2.2^c*	1, 2.0 ± 2.0^a*, b*
Sexual satisfaction 29-item scale (SRI)^2	77, 77.9 ± 21.9^b**	96, 91.7 ± 16.9^a**, c**	90.5, 86.3 ± 18.6^b**
SRI Sex-positive and partner-affirming statements subscale^2	30, 28.4 ± 17.4^b**	43, 39.4 ± 13.7 ^a**, c***	39, 33.7 ± 16.9^b***
SRI Sex negative statements about sex with partner subscale	26.0 ± 2.5	25.3 ± 3.4	25.6 ± 3.4
SRI Sex-positive complaints about sex with partner Subscale	25, 23.4 ± 7.2^b*, c*	28, 27.1 ± 5.1^a*	28, 27.0 ± 5.1^a*
Hypersexuality and risky sexual behaviors with men scale	6.6 ± 2.2^b***,c***	4.5 ± 2.4^a***	4.1 ± 2.4^a***
Hypersexuality male partner subscale^2	5, 5.1 ± 1.4^b*,c***	4, 3.9 ± 1.9^a*	4, S3.6 ± 1.9^a***
Risky sexual behaviors with men subscale^2	1, 1.4 ± 1.2^b***,c***	0, 0.6 ± 0.9^a***	0, 0.5 ± 1.0^a***
Hypersexuality and risky sexual behaviors with women scale	7.0 ± 2.5^c***	5.8 ± 2.8^c***	4.7 ± 2.6^a***,b***
Hypersexuality female partner subscale^2	5, 5.1 ± 1.4^c**	4, 4.2 ± 2.0	4, 3.8 ± 1.9^a**
Risky sexual behaviors with women subscale^2	2, 1.9 ± 1.4^c***	1, 1.6 ± 1.4^c***	0, 0.9 ± 1.2^a***,b***
Male-male orientation scale (M-MSOS)^2	0, 2.2 ± 4.0^b**,c**	0, 0.4 ± 1.6^a**	0, 1.0 ± 2.8^a**
Male-female orientation scale (M-FSOS)^2	10, 8.4 ± 3.6	10, 9.5 ± 1.7^c***	9, 8.3 ± 2.9^b***
Adult behavioral sexual orientation scale^2,3	0, 15.8 ± 31.5^b***,c***	0, 2.7 ± 13.3^a***	0, 8.2 ± 26.3^a***

Note. ^acomparison to brother-sister incest group, ^bcomparison to CSA-AF group, ^ccomparison to control group: * = p < .05, ** = p < .01, *** = p < .001, using the Tukey-Kramer correction for multiple post-hoc comparisons. ¹Medians are provided only for variables with heterogeneous variance. ²Variance was heterogeneous. We used rank-transformed data to calculate the p-values and provided medians as well as the means and standard deviations. ³The ns in the three groups were reduced to 24, 114, and 827 from left to right, respectively, because the scores could not be computed in participants who reported no sexual activity as adults.

The Hypersexuality and Risky Sexual Behavior Scales

The hypersexuality and risky sexual behavior with men and the hypersexuality and risky sexual behavior with women scales (HSRSB-M and HSRSB-W, respectively) are covert measures based on face-valid items derived using reliability analysis and factor analysis. The scales each consist of 13 self-statements presented as agree/disagree coded 1/0, respectively, and scored by summing the individual item (0 or 1) scores, with theoretical maximum and minimum scores of 13 and zero, respectively. The 13 self-statement items comprising each scale (Griffee et al., 2012) were semi-randomized among a total of 174 self-statements, which effectively hides the fact that the some self-statements are used to produce scales. Each scale is composed of the hypersexuality (items 1–8) and the risky sexual behaviors (items 9–13, Griffee et al., 2012). Four items in the scales (items, 7, 9, 10, and 12) contain the word “men” in HSRSB-M. Alternative items for 7, 9, 10, and 12 which substitute the word “women” are used in HSRSB-W to describe interactions with women. Internal consistency of the HSRSB-M scale was Kuder-Richardson formula 20 α = .691. A frequency distribution of the actual total scores showed that 96% of the 1,178 participants had scores below 9, 92% had scores below 8, and 85% had scores below 7. Internal consistency of the HSRSB-W scale was Kuder-Richardson formula 20 α = .706. A frequency distribution of the actual total scores showed that 95% of the 1,178 participants had scores below 10 and 90% had scores below 9, 84% had scores below 8, and 75% had scores below 7. These findings were consistent with the observations that the median score on the HSRSB-M scale was 4 while the median score on the HSRSB-W was 5 and that to get scores above 6 on either of the two scales, a participant would have had to endorse one or more of the last seven items, which all describe risky sexual behaviors and which were all consistent with sexual addiction. Twenty-five percent of the participants in the present study had scores above 7 on the HSRSB-W, indicating the high prevalence of risky sexual behaviors with women among the male participants.

The Male-male Sexual Orientation Scale (M-MSOS)

We summed the data from 12 of the items in Table 9 of Beard et al. (2013) to obtain the total score for the M-MSOS (all but Item 34, the self-identified sexual orientation and Items 30–32, which were obligatory subsets of item 29). The score on the M-MSOS should be interpreted as a count of the number of scale items or behaviors that the participant endorsed. The M-MSOS alpha was 0.9608; 81.1% of the participants had scores of 0, 90% had scores less than 3, and 94.8% had scores of less than 10.

Table 9 Multiple Linear Regression Models for Predicting Adult Sexual Orientation

Variable^1	n1^2	B	SE	p	Effect size^3
Model # 24 Male-female Sexual Orientation Scale, R^2 = .195
Sex of any kind with a…
male under 18	152	−3.460	0.325	<.001	.088
female of any age	610	1.207	0.156	<.001	.049
Cross products: Sex of any kind with a… X Sex of any kind with a…
Male under 18 X female under 18	81	1.829	0.435	<.001	.015
Adult male X adult female	4	5.679	1.387	<.001	.014
Male under 18 X adult male	23	−2.469	0.619	<.001	.013
Constant		8.171	0.112	<.001	.820
Model # 25 Male-male Sexual Orientation Scale, R^2 = .366
Sex of any kind with a…
male under 18 years old	152	5.185	0.282	<.001	.224
Cross products: Sex of any kind with a… X Sex of any kind with a…
Male under 18 X female under 18	81	−2.100	0.380	<.001	.025
Male under 18 X adult male	23	3.740	0.534	<.001	.040
Adult male X adult female	4	−4.363	1.197	<.001	.011
Sex of any kind with a…
Female under 18	574	−0.467	1.197	<.001	.010
Constant		0.614	0.094	<.001	.035

Note. ¹Predictors are listed from top to bottom in order of decreasing predictive power as determined by order of stepwise addition to the model. ²n1 Observed number of ones in the 0/1 dummy predictor. ³Effect size as measured by the partial eta squared.

The Male-female Sexual Orientation Scale (M-FSOS)

We summed the data from the twelve items analogous to the twelve above and identical to those in Table 9 of Stroebel, O’Keefe, Griffee et al. (2013) to obtain the total score for the M-FSOS. The M-FSOS alpha was 0.8396; 3.7% of the 1,178 participants had scores of 0. Conversely, 96.3% had scores of greater than 0, 93.3% had scores greater than 1, and 91.9% had scores greater than 2.

Content Validity

All items for the survey were carefully reviewed and approved by four doctoral level experts in the field: a psychiatrist trained in psychotherapy, a social worker trained in psychotherapy, a psychologist, and a gynecologist who was also trained in psychology.

Procedure

The present study was part of a larger study entitled “Effects of Recalled Family Attitudes and Childhood Sexual Experiences on Adult Sexual Attitudes and Adjustment,” approved by the institutional review boards at Marshall University, Charleston Area Medical Center/West Virginia University, West Virginia University, West Virginia State University, and Concord University. All 1,178 participants were over the age of 18 and gave informed consent using printed paper forms approved by the relevant institutional review board. Potential participants were invited to participate in a cradle to the grave study on human sexuality. The research was conducted using the S-SAPE1 computerized anonymous survey instrument (Beard et al., 2013; Stroebel et al., 2012). Surveys were administered in university computer laboratories that had up to 45 computers to a room, and sufficient space between participants so that others were not in a position to see their computer screens. Anonymity was protected by electronic randomized filing of the encrypted results in a hidden random access file filled with fake data as well as simultaneous filing of many fake decoy lines. Decoding was performed on the file containing all respondents’ randomly filed encrypted data. During a 10-minute orientation respondents were informed of these protections to their anonymity and that the S-SAPE1 computerized anonymous survey instrument was designed to obtain a history of sexual experiences and behaviors, and they were again informed that they could withdraw from the study at any time they wished. No reference to incest was made during promotion of the study. During the orientation provided before the participants started entering their data into the computers they were informed about the operation of the screen that presented the sexual behavior items and the sexual behavior sub-items. They were informed that for each behavior they would be asked whether a brother or sister or a mother or a father had been a partner. Items related to incest were presented interspersed among similar items not related to incest. Variables describing behaviors that constituted CSA by an adult female were constructed by the computer program to insure that they were worded similarly to those previously presented that described the same behaviors with female partners (a) whose age was within 4 years of the participant's and (b) whose age was more than 4 years older than the participant's but under age 18.

Selection of Participants for the Study

From the records of all 1,199 male and 2,051 female potential participants available in the database, we selected all 1,178 men who were not transsexual. The 20 transsexual men were excluded because at the time that the early sexual behaviors occurred, they were genetic and anatomical females; any sexual behaviors with a sister would have constituted sister-sister incest; and any sexual behavior with an adult female would have constituted CSA of an under-age female victim by an adult female perpetrator.

RESULTS

For the purposes of statistical analysis, those who admitted to having participated in any voluntary or coerced sexual behaviors with one or more sisters but who denied that their mother had been a partner were assigned to the SBI group (n = 27, Table 1). In no case did the SBI, itself, progress to either voluntary or coerced intra-vaginal coitus with the sister-perpetrator. Those who admitted to having participated in voluntary or coerced sexual behaviors of any kind with adult female partners but who denied that their sister had been a partner were assigned to the CSA-AF group (n = 119, one of whom was the participant's mother). Those who denied having participated in any one of the voluntary or coerced behaviors with sisters, mothers, or adult female partners were assigned to the control group (n = 1,032).

Table 1 Voluntary, Voluntary and Coerced, and All Coerced Participation in Sister-Brother Incest by Age-differential Between the Siblings

	Participation of participant in sister-brother incest
	All voluntary		Both voluntary and coerced		All coerced
	n	Row%	n	Row%	n	Row%
Sister was within 4 years of participant's age: n = 24^1	17	70.8	5	20.8	2	8.3
Sister was more than 4 years older than participant but under 18: n = 5^1	4	80.0	1	20.0	0	0.0
Sister was more than 4 years older than participant and over 18: n = 0^1	0	—	0	—	0	—
Sister was more than 4 years younger than participant: n = 2^1	2	100.0	0	0.0	0	0.0

Note. ¹The total of the ns add to 31 because 4 of the 27 participants who were victims of sister-brother incest provided data on sisters in more than one age-differential group.

Voluntary or coerced coitus before age 18 with an adult female had been experienced by 2 (7.4%) of those in the SBI group and 90 (75.6%) of those in the CSA-AF group, (χ²[2, N = 1,178] = 499.36, p < .001). Voluntary or coerced coitus before age 18 with a female of any age had been experienced by 14 (51.9%) of those in the SBI group, 101 (84.9%) of those in the CSA-AF group, and 308 (29.8%) of controls (χ²[2, N = 1,178] = 143.44, p < .0010, indicating significant differences in the percentages among the three groups. The data on ten psychological scales and three sets of subscales are presented in Table 2. In Tables 3–6 the data presented for all participant-groups included both voluntary and coerced behaviors (since both constituted incest), and they were also summed to include sexual partners from each partner-age differential group. The numbers of female partners with whom participants engaged in each of the behaviors are presented in Table 3. The numbers of times that they engaged in each behavior are presented in Table 4. The earliest age (Table 5) and the latest age (Table 6) are the ages that they engaged in either voluntary or coerced behavior with a partner from any age-differential group. The 1,178 participants included in the present study were the same participants also included in the study reported by Beard et al. (2013) which used an analogous study design to analyze the effects of brother-brother incest (BBI, 25 cases) and child sexual abuse by an adult males (CSA-AM, 26 cases). There was only 1 (3.7%) of the 27 SBI cases where the participant also was included among the 25 BBI cases and only 6 (5.0%) of the 119 CSA-AF cases where the participant was either included among the 26 CSA-AM cases (4 cases) or among the 25 BBI cases (2 cases) analyzed by Beard et al. (2013). In the present study we have controlled for the effects of BBI and CSA-AM by using the treatment group variable in the Beard et al. (2013, coding for BBI, CSA-AF, and controls) as the blocking factor in the two-way ANOVAs used to test for between group differences in Table 2. In the logistic regressions presented in Table 7, we evaluated 0/1 dummy predictors for SBI, CSA-AF, BBI, and CSA-AM to control for effects of BBI and CSA-AM when they were statistically significant in the model.

Table 3 Number of Partners for Voluntary or Coerced Behaviors with Female Partners from All Age-Differential Categories

		SBI			CSA-AF			Controls
Behavior		Mdn	range	n	Mdn	range	n	Mdn	range	N
A	Of any kind	4^b***	1–26	27	9^a***, c***	1–225	119	3.5^b***	1–200	464
B	Touching your female partner's breasts	4.5^b**	1–31	20	11^a**,c***	1–185	113	4^a***	1–120	427
C	Female partner looking at your genitals	5	1–25	17	11^c***	1–135	93	3^b***	1–225	330
D	Looking at your female partner's genitals	3.5^b**	1–24	22	11^a**,c***	1–155	93	3^b***	1–1090	340
E	Touching your female partner's genitals	4.5^b*	1–31	20	9.5^a*, c***	1–222	108	3^b***	1–558	406
G	Having the female partner touch your genitals	4^b**	1–21	20	10^a**,c***	1–160	107	3^b***	1–100	377
H	Inserting of your penis into your female partner's vagina	3	1–23	14	8	1–222	101	2	1–151	308

Note. ^acomparison to sister-brother incest group, ^bcomparison to CSA-AF group, ^ccomparison to Control group. * = p < .05, ** = p < .01, *** = p < .001, using the rank-t test and the Turkey-Kramer correction for multiple post-hoc comparisons.

Table 4 Number of Times for Voluntary or Coerced Behaviors with Female Partners from all Age-Differential Categories

		SBI			AF			Controls
Behavior		Mdn	range	n	Mdn	range	n	Mdn	range	n
A	Of any kind	18^b**	2–1949	27	90^a**,c***	1–2498	119	40^b***	1–1999	464
B	Touching your female partner's breasts	56^b*	1–200	20	101^a*,c***	1–3097	113	50^b***	1–1999	427
C	Female partner looking at your genitals	60	1–1240	17	100	1–1998	93	30	1–1999	330
D	Looking at your female partner's genitals	23.5	2–1580	22	100^c***	3–1999	93	35^b***	1–1999	340
E	Touching your female partner's genitals	50	1–1360	20	101^c***	1–2498	108	50^b***	1–1999	406
G	Having the female partner touch your genitals	23.5^b*	2–1580	22	100^a*,c**	3–1999	93	35^b**	1–1999	340
H	Inserting of your penis into your female partner's vagina	43^b*	1–170	14	102^a*,c**	1–2997	101	50^b**	1–1999	308

Note. ^acomparison to sister-brother incest group, ^bcomparison to CSA-AF group, ^ccomparison to Control group. * = p < .05, ** = p < .01, *** = p < .001, using the rank-t test and the Turkey-Kramer correction for multiple post-hoc comparisons.

Table 5 Earliest Age for Voluntary or Coerced Behaviors with Female Partners from all Age-Differential Categories

		SBI			CSA-AF			Controls
Behavior		Mdn	Range	n	Mdn	Range	n	Mdn	Range	n
A	Of any kind	8^b***,c***	1–16	27	15^a***	3–17	119	15^a***	3–17	464
B	Touching your female partner's breasts	14	5–17	20	14	1–17	113	15	1–17	427
C	Female partner looking at your genitals	8^b**,c***	4–16	17	14^a**	3–17	93	15^a***	3–17	330
D	Looking at your female partner's genitals	8.5^b***,c***	3–15	22	15^a***	4–17	93	15^a***	3–17	340
E	Touching your female partner's genitals	10 ^b***,c***	4–15	20	15^a***	5–17	108	15^a***	3–17	406
G	Having the female partner touch your genitals	14^b*,c***	4–17	20	15^a*	6–17	107	15^a***	2–17	377
H	Inserting of your penis into your female partner's vagina	14.5	6–17	14	15	5–17	101	16	1–17	308

Note. ^acomparison to sister-brother incest group, ^bcomparison to CSA-AF group, ^ccomparison to Control group. * = p < .05, ** = p < .01, *** = p < .001, using the rank-t test and the Turkey-Kramer correction for multiple post-hoc comparisons.

Table 6 Latest Age (Before Reaching Age 18) for Voluntary or Coerced Behaviors with Female Partners from all Age-Differential Categories

		SBI			CSA-AF			Controls
Behavior		M^1	Range	n	M^1	Range	n	M^1	Range	n
A	Of any kind	15.1b***,c***	6–17	27	16.8^a***	4–17	119	16.4^a***	5–17	464
B	Touching your female partner's breasts	16.1^b***,c***	10–17	20	16.9^a***	13–17	113	16.8^a***	7–17	427
C	Female partner looking at your genitals	15.3 ^b***,c***	8–17	17	16.7^a***	4–17	93	16.5^a***	5–17	330
D	Looking at your female partner's genitals	15.3 ^b***,c***	5–17	22	16.9^a***	11–17	93	16.3^a***	6–17	340
E	Touching your female partner's genitals	15.2 ^b***,c***	5–17	20	17.0^a***	15–17	108	16.7^a***	6–17	406
G	Having the female partner touch your genitals	15.8 ^b***,c***	8–17	20	17.0^a***	15–17	107	16.8^a***	5–17	377
H	Inserting of your penis into your female partner's vagina	16.6^b*,c*	14–17	14	17^a*	15–17	101	16.8^a*	7–17	308

Note. ^acomparison to sister-brother incest group, ^bcomparison to CSA-AF group, ^ccomparison to Control group. * = p < .05, ** = p < .01, *** = p < .001, using the rank-t test and the Turkey-Kramer correction for multiple post-hoc comparisons. ¹Means are provided because all median values were 17 years of age.

Table 7 Items with Categorical Responses

	Groups			Odds Ratio^4 and Significance^5 vs.
				Controls^6 and Model #
	SBI^7	AF^8	C^9
Item and model #	%^13	%^13	%^13	SBI^7	AF^8	BBI^10	AM^11	M#^12
Item 5. I feel like damaged goods	25.9	5.9	4.7	6.8^2***	ns^14	4.3^3,15	15.7^1***	1
Item 6. I have suffered psychological injury	33.3	5.9	4.6	10.8^2***	ns^14	7.9^3***	13.5^1***	2
Item 7. Distant from both parents or distant from mother and close to father in high school	29.6	26.1	16.5	ns^14	ns^14	3.7^2*	6.6^1***	3
Item 10. Only way that the adult(S) that I had sexual experiences with as a child have ever appeared in any of my dreams was in nightmares and the feeling was terror or horror	3.7	1.7	0.9	ns^14	ns^14	ns^14	15.2^1***	4
Item 11. I have cheated by having sex with women	18.5	37.0	19.7	ns^14	2.3^1***	ns^14	ns^14	5
Item 12. I have cheated by having sex with men	22.2	6.7	6.5	3.9^3,15	ns^14	10.2^2***	11.3^1***	6
Item 14. I have undergone psychological treatment for my childhood sexual abuse	22.2	3.4	2.2	12.3^2***	ns^14	ns^16	27.7^1***	7
Item 15. When I tried to open up with another person about my childhood sexual experience, he/she reacted with horror and disgust	11.1	5.9	3.4	ns^15	ns^14	ns^14	7.8^1***	8
Item 16. I have not discussed all of my childhood sexual experience with my spouse or long-term partner cecause I felt that he/she might not handle it well	51.9	30.3	23.8	3.2^2*	ns^14	2.7^3	4.5^1***	9
Item 18. I am more distant from that (those) sisters(s) (with whom I experimented)	22.2	0.0	0.5	65.5^1***	ns^14	ns^14	ns^14	10
Item 19. The only way that the children that I had sexual experiences with as a child have ever appeared in any of my dreams was in nightmares and the feeling was terror or horror	3.7	0.0	0.5	ns^16	ns^14	9.6^1*	ns^16	11
Item 21. I believe that in some ways I have demonstrated symptoms of “sexual addiction” or “sexual compulsions” which may explain some of my sexual behaviors.	74.1	42.9	36.8	4.9^2**	ns^14	ns^14	5.2^1***	12
Item 22. I have sought treatment for “sexual addiction,” “sexual compulsivity,” or a related sexual diagnosis or I have been a member of a 12-step group for such a problem	18.5	6.7	3.6	5.1^3*	ns^14	7.5^2***	11.7^1***	13
Voluntary or coerced sex of any kind with females who were under age 18 before reaching age 18	100.0	73.1	45.0	†^2	3.3^1***	ns^14	ns^14	14
Voluntary or coerced sex of any kind with males who were under age 18 before reaching age 18	48.1	9.2	13.2	7.7^3***	ns^14	††^1	51.9^2***	15
Voluntary sex with adult males as an adult
(A) Sex of any kind	33.3	6.7	10.0	4.8^3**	ns^14	11.1^2***	15.8^1***	16
(J)  Reaching orgasm (with a male partner)	25.9	5.9	9.2	3.53^3*	ns^14	12.4^2***	15.1^1***	17
(K) Ejaculating in your male partner's rectum	18.5	3.4	5.9	3.5^3,15	ns^14	12.5^2***	13.8^1***	18
(L) Ejaculation as a result of oral stimulation of your penis	25.9	5.9	8.6	3.8^3*	ns^14	11.4^2***	19.3^1***	19
(M) Reaching orgasm as a result of manual stimulation of your penis	22.2	5.0	7.4	3.6^3,15	ns^14	11.5^2***	17.0^1***	20
(N) Bringing your male partner to orgasm by dtimulating his penis with your mouth	22.2	3.4	7.5	3.5^3,15	ns^14	6.2^2***	16.7^1***	21
(O) Bringing your male partner to orgasm by stimulating his penis with your hand	22.2	4.2	7.3	3.6^3,15	ns^14	9.62***	14.6^1***	22
(R) Sexual relations with a male prostitute	11.1	0.0	1.3	9.0^2*	ns^14	9.8^1*	7.0^3*	23

Note. ¹Most powerful predictor, added first in the multiple logistic regression analysis. ²Second most powerful predictor, added second in the multiple logistic regression analysis. ³Third most powerful predictor, added third in the multiple logistic regression analysis. ⁴The adjusted odds ratio shows the predicted increase in likelihood over controls of agreeing with the statement or engaging in the behavior (adjusted for all predictors in the model). ⁵A Bonferroni correction has already been applied to every p-value in this table: Each presented p-value was multiplied by 4 to correct for the 4 comparisons made. * = p < .05, ** = p < .01, and *** = p < .001. ⁶Controls for the odds-ratio vs. controls comparisons are the 989 participants who were not included in the SBI, CSA-AF, BBI, or the CSA-AM groups. ⁷SBI: n = 27. ⁸AF (CSA-AF): n = 119. ⁹C (controls for percentage calculations): n = 1,032. ¹⁰BBI: n = 25. ¹¹AM (CSA-AM): n = 26. ¹²Model #. ¹³All percentages are for those who agreed with the statement or engaged in the behavior. The percent that disagreed or did not engage in the behavior can be found by subtraction. ¹⁴ns: not significant at step-0 of the logistic regression analysis. ¹⁵A significant predictor in the equation before applying the (times 4) Bonferoni correction. ¹⁶ns: significant at step-0 but not a significant predictor once the more powerful predictors had been entered into the model. †All participants who were SBI victims had voluntary or coerced sex with a female under 18 before reaching 18, making it impossible to calculate an odds-ratio. ††All participants who were BBI victims had voluntary or coerced sex with a male under 18 before reaching 18, making it impossible to calculate an odds-ratio. Items 9, 13, and 17 (Appendix A) were tested but not shown because neither SBI nor CSA-AF were significant predictors.

Hypothesis Testing

Child Sexual Abuse by Female Perpetrators has Global Adverse Effects on Male Victims

As adults, the participants who were victims of SBI had significantly more problematic scores than the control group on the conflicts scale and significantly more problematic scores than the CSA-AF group on the sexual satisfaction scale (Table 2). The victims of SBI had significantly more problematic scores than either the control group or the CSA-AF group on the Sex-positive Complaints about Sex with Partner subscale and on the hypersexuality and risky sexual behaviors with men scale as well as on the two subscales. The victims of SBI had significantly more problematic scores than the control group on the hypersexuality and risky sexual behaviors with women scale as well as on the two subscales. Victims of SBI had significantly more problematic responses to 8 of the first 13 items, and victims of CSA-AF had more problematic responses to one of the first 13 items requiring categorical responses listed in Table 7 than the men in the control group.

Victims of CSA-AF had more problematic scores than the controls on the conflicts scale, but the victims of CSA-AF actually had less problematic scores on the sexual satisfaction scale than the controls and less problematic scores than the SBI group on the Sex-positive Complaints about Sex with Partner subscale. The victims of CSA-AF had significantly more problematic scores than the control group on the hypersexuality and risky sexual behaviors with women scale as well as on the risky sexual behaviors with women subscale. Victims of CSA-AF experienced their first coitus with a female significantly earlier than either the SBI group or the control group when coitus with females of all age groups was considered (Table 8). Furthermore, for voluntary or coerced sex of any kind before age 18 with female partners under age 18, the median number of 8 partners for those in the CSA-AF group was significantly higher than the corresponding median number of 3.5 female partners in the control group and 4 female partners in the SBI group (Table 8). The median number of 90 times for those in the CSA-AF group was significantly higher than the corresponding median numbers of 40 times in the control group and 18 times in the SBI group.

Table 8 Early Experience with Young Partners, First Orgasm, First Coitus with a Female, and Sex with Adults as an Adult

	Sister-brother Incest n = 27		CSA-AF n = 119		Controls n = 1032
Behavior	Mdn, Mean ± SD	n	Mdn, Mean ± SD	n	Mdn, Mean ± SD	n
Age at first orgasm	12, 11.3 ± 3.1^b*,c***	27	13, 12.6 ± 2.1^a*	118	13, 13.0 ± 2.4^a***	1019
Age at first coitus with a female^2	17, 17.7 ± 4.1^b**	23	16, 15.4 ± 2.6^a**,c***	115	16, 16.6 ± 3.2^b***	885
(A) Sex of any kind with females who were under age 18 before the participant reached age 18
Earliest age^2	8, 8.6 ± 3.9^b***,c***	27	14, 13.7 ± 2.6^a***	87	15, 13.7 ± 3.1^c***	464
Number of partners^2	4, 5.2 ± 5.5^b**	27	8, 16.0 ± 27.1^a**,c***	87	3.5, 6.9 ± 13.1^b***	464
Number of times^2	18, 119 ± 372^b***	27	90, 246 ± 376^a***,c***	87	40, 127 ± 246^b***	464
Latest age^2	17, 15.1 ± 3.1^b***,c***	27	17, 16.9 ± 0.7^a***	87	17, 16.4 ± 2.1^c***	464
(I) Sex of any kind with an adult female after age 18^1
Number of partners^2	10, 35 ± 84^c**	23	6, 31 ± 106^c***	114	3.5, 11 ± 26^a**,b***	788
Number of times^2	500, 567 ± 419^b*,c**	23	175, 330 ± 368^a*	114	100, 276 ± 336^a**	788
(J) Intravaginal ejaculation with an adult female after age 18^1
Number of partners^2	9, 35 ± 79^c***	20	3, 36 ± 130^c*	75	2, 14 ± 66^a***,b*	526
Number of times^2	350, 485 ± 410^c**	20	100, 315 ± 386	75	100, 247 ± 334^a**	526
(A) Sex of any kind with males who were under age 18 before the participant reached age 18
Earliest age	8, 9 ± 3.6	13	10, 10.4 ± 3.4	11	11, 10.7 ± 3.8	136
Number of partners	4, 4.6 ± 4.0	13	3, 4.5 ± 5.7	11	2, 5.8 ± 13.1	136
Number of times^2	10, 175 ± 520	13	20, 26 ± 31	11	10, 81 ± 212	136
Latest age	13, 13.5 ± 3.2	13	15, 13.8 ± 2.9	11	15, 14.0 ± 3.4	136
(A) Sex of any kind with an adult male after age 18^1
Number of partners	10, 71 ± 90	9	15, 79 ± 113	8	12, 82 ± 175	103
Number of times	200, 168 ± 178	9	50, 276 ± 448	8	100, 304 ± 377	103

Note. ¹Includes only voluntary sexual behaviors. ²Variance was heterogeneous, and statistical analyses were performed on the rank-transformed variable. Note: ^acomparison to brother-sister incest group, ^bcomparison to CSA-AF group, ^ccomparison to control group, * = p < .05, ** = p < .01, *** = p < .001, using one-way ANOVA and the Turkey-Kramer correction for multiple post-hoc comparisons.

The median earliest age participants began sexual behaviors of any kind with female partners younger than age 18 for the SBI group (8 years old) was significantly younger than that for either the CSA-AF group or the control group. Similarly, the average latest age participants engaged in sexual behaviors of any kind with female partners younger than age 18 for the SBI group (15.1 years old) was also significantly younger than that for either the CSA-AF group or the control group (Table 8). Thirteen (48.1%) of the 27 victims of SBI, only 11 (9.2%) of the 119 victims of CSA-AF, and 140 (13.6%) of the 1,032 in the control group reported having voluntary or coerced sex of any kind with a male partner before reaching the age of 18. Victims of SBI had significantly higher scores on the male-male sexual orientation scale and the adult behavioral sexual orientation scale than either the control group or the CSA-AF group (Table 2), findings explained by long-term effects in the 48.1% who had engaged in sexual behaviors with other male partners under the age of 18 before reaching 18 years of age (Table 7). Logistic regression analysis showed that the likelihood of engaging in sex of any kind with male partners was 7.7 times higher before 18 years of age in SBI incest victims than in the controls (Model 15) and 4.8 times higher after 18 years of age in SBI incest victims than in the controls (Model 16, Table 7). Furthermore, addition of two more 0/1 dummy variables (predictor #1, sex of any kind with a male under 18 years of age before reaching the age of 18 and predictor #2, sex of any kind with a female under 18 years of age before reaching the age of 18) to the set of four predictors used to obtain the results in Models 1–23 in Table 7 showed that predictor #1 (above) was a far more powerful predictor than any of the other variables in Model #16 in Table 7 and that neither predictor #2 nor sex of any kind with an adult female before reaching the age of 18 were statistically significant predictors at step 0 of the logistic regression. After adding the most powerful predictor (predictor #1) to the model, none of the other variables that were statistically significant predictors at step 0 remained statistically significant. Participants who had engaged in either voluntary or coerced partner sex with another male before reaching 18 years of age were approximately 30 times as likely (as those who had not) to report having voluntarily engaged in sex with another adult male after reaching 18 years of age (the odds ratio, 95% CI, and p-value even after a 6-times Bonferroni correction were 30.1[19.1–47.5], p < .001 for coerced SBI vs. controls). The Nagelkerke R square with only a single predictor in the model (.386) was 2.8 times higher than that of Model #16 with three predictors in Table 7 (.137). These results were consistent with the idea that sex with young male partner before reaching the age of 18 was the most powerful predictor of actually having voluntary sex with an adult male as an adult. Furthermore, logistic regression showed that neither having participated in sex of any kind with a female of any age, with a female under 18 years of age, nor with an adult female before reaching 18 years of age was a statistically significant predictor either for having sex of any kind with a male of any age, or with a male under age 18, or an adult male before reaching 18 years of age.

Similarly, testing the same set of six variables as predictors of the M-MSOS using multiple linear regression showed that, in the order of decreasing predictive power, the 0/1 dummy variables #1 and #2 (above) and sex with an adult male before reaching 18 years of age were the three variables whose statistically significant inclusion in a single equation eliminated the remaining variables as significant predictors. The regression coefficient of variable #2 was negative indicating that sexual experience with a female partner under the age of 18 tended to inhibit development of a male-male sexual orientation.

By substituting sex of any kind with a male of any age before reaching 18 years of age and sex of any kind with a female of any age for the two sibling incest predictors and adding all the first-degree cross products between the primary predictors, we created and tested a set of six primary variables and their first degree cross-products as predictors of the M-MSOS and M-FSOS using multiple linear regression. This approach greatly increased the power and the accuracy of the regressions by taking account of all sexual interactions of all participants with male and female partners before they had reached 18 years of age. Of the 1,178 participants, 610 reported “sex of any kind” with females of any age (119 with adult females and 574 with females under 18 years of age). Of the 1.178 participants, 164 reported “sex of any kind” with males of any age (28 with adult males and 152 with males under 18 years of age). Step-wise regression procedures arrived at two multiple regression statistical models: one for predicting the participants’ adult male-female sexual orientation as measured by M-FSOS (Model #24, Table 9) and the other for predicting the participants’ adult male-male sexual orientation as measured by the M-MSOS (Model #25, Table 9). The predictors included in the two models were different because they were selected solely based on their predictive power for the two different dependent variables. The constant term of 8.171 indicated that participants who had no reported early experience with female or male partners had a strong tendency to develop a male-female sexual orientation as a default outcome, suggesting that the “heterosexual” bias of the culture in which they developed did have a strong influence on their adult male-female sexual orientation. The second predictor in Model #24 included the early sexual experience of the 610 participants with female partners of any age, implying that any sexual experience with a female partner tended to produce conditioning of a male-female sexual orientation. The other terms added or subtracted from the effect related to the early sexual experience of the 610 participants with female partners of any age. Model #24 showed negative regression coefficients for the two predictors exclusively describing sex with male partners, providing evidence for reduction in the male-female orientation by early experiences with male partners. The positive sign of the cross products in Model #24 involving sexual experiences with female partners provided evidence that counter-conditioning reduced the inhibitory effect of sexual experiences with male partners on the participants’ male-female sexual orientation.

Because the sign of each regression coefficient in Model #25 for a primary variable related exclusively to sexual behaviors with male partners was positive and the sign of each regression coefficient related to sexual behaviors with females and each cross-product with such a variable was negative, Model #25 provided unequivocal evidence supporting the idea that sexual early behaviors with male partners tended to condition an adult male-male sexual orientation and that early sexual behaviors with female partners tended to inhibit development of an adult male-male sexual orientation in that participant. This was also unequivocal evidence of of counter-conditioning produced by sexual experiences with females. In our study, the age at which the 1,164 participants reported their first orgasm was 13.0 ± 2.4 with a median age of 13 years, and the first orgasm of the 163 who had sex of any kind with a male partner of any age was at an age that was significantly younger than that of the 1,001 who had not had such an experience (11.7 ± 2.5 vs. 13.2 ± 2.3 with medians of 12 and 13 years of age, respectively, p < .001). Furthermore, the age at first orgasm was significantly negatively correlated with the M-MSOS (r = -.108, p < .001) but not the M-FSOS (r = −.013, ns). The remaining 14 participants were left out of these analyses because they denied having ever had an orgasm, requiring treatment of their entry as missing data. Forcing the age at first orgasm into the regression as a predictor in addition to those included in Model #25 showed that age at first orgasm was not a significant predictor after adjusting for the other predictors in the model. This result implied that the significant correlation between age at first orgasm and the male-male sexual orientation score was completely explained by the behaviors with partners described by the other predictors. The small size of the constant in Model #25 (0.614) relative to that for Model #24 was consistent with the idea that the heterosexual bias of the societies in which our participants developed provided little impetus to developing a same-sex orientation when conditioning was not available from same-sex partners. Neither the number of older brothers, nor the number of older sisters, nor the number of younger brothers, nor the number younger sisters was significantly correlated with either the M-MSOS or the M-FSOS score, whether tested as the actual count or as a 0/1 dummy variable (coding for whether or not there was an older brother, etc.).

The earliest age of at which the 160 participants (13, 11, and 136 from the SBI, CSA-AF, and Control groups, respectively; Table 8) included in variable #1 had voluntary or coerced sexual experiences with other males was 10.5 ± 3.7 (mean ± SD, with median = 11) years of age. After reaching age 18, victims of SBI and victims of CSA-AF had sex with a significantly larger number of female partners than controls. Although not shown in Table 3, by the time that they reached their 18^th birthday, the 119 victims of CSA-AF estimated that they had engaged in sex of any kind with a total of 706 adult females (an average of 5.9 partners each), and the 91 who had gone on to have coitus with their adult female perpetrators estimated that they had engaged in coitus with 756 adult female perpetrators (an average of 8.3 partners each). In contrast, by the time that they reached their 18^th birthday, the 27 victims of SBI had engaged in sex of any kind with a total of only two adult female perpetrators, and they had experienced coitus with only two adult female perpetrators (an average of 0.07 each, none of whom were sisters). The victims of CSA-AF had significantly higher scores on the Male-female Orientation Scale (M-FSOS) than either the control group or the SBI group.

Child Sexual Abuse Perpetrated by a Sister Starts Earlier Than CSA-AF

The participants who were victims of SBI were initiated into five of the behaviors significantly earlier than the participants in the CSA-AF group, at median ages ranging from 6 to 14.5 years of age (Table 5). Based on the median earliest ages at which those in the SBI group were initiated into each behavior, the sequence of behaviors was: perpetrator looked at victim's genitals (age 8), victim looked at perpetrator's genitals (age 10), victim touched the perpetrator's genitals (age 10), perpetrator touched victim's genitals with her hand (age 14), and victim touched perpetrator's breasts (age 14).

SBI is Often the First Sexual Experience for the Brother

Fourteen of the 27 victims of SBI reported no same-sex experience before age 18, showing that their first partner-sex experience was with their sister. Thirteen of the 27 victims of SBI also reported voluntary or coerced sexual experience with a male partner before age 18; in 53.8% of the 13 cases the SBI preceded the same-sex experience by a year or more, in 23.1% of the 13 cases the BSI and the same-sex experience occurred within the same year, and in 23.1% of the 13 cases the same-sex experience preceded the SBI by a year or more. Thus, for 21 (78%) of the 27 SBI cases, the sexual experience with their sister was their first experience with partner-sex. Twenty-six of the 27 victims of SBI had begun masturbating before age 18. In 16 cases (59.3% of the 27 SBI cases) SBI preceded onset of masturbation for the brother, in another 4 cases both occurred within the same year and in 22% the onset of masturbation had preceded SBI by a year or more. The one-sample t-tests on the age-differences in the 26 who had participated in both SBI and masturbation showed that the tendency of SBI to precede onset of masturbation in the brothers was statistically significant (t = −2.3, p = .014). These data showed that the eroticization process described by Yates (1982) was begun by the brother's sexual experience with his sister in 19 (70%) of the 27 cases (rather than by masturbation or sex with other males). In comparison to the controls, there was a statistically significant increase in the likelihood that victims of SBI would engage in masturbation before and after age 18 (Table 10).

Table 10 Incidence, Odds Ratios, and Their 95% Confidence Limits for Four Measures of Self-Masturbation Before and After Reaching 18 Years of age

	Groups			Odds Ratio^2 and
				Significance^3
	SBI	CSA-AF	Controls
	n = 27	n = 119	n = 1032	SBI vs.	CSA-AF vs.
	% Yes^1	% Yes^1	% Yes^1	Controls	Controls
Masturbation behaviors before age 18
Masturbation involving a vibrating device.	7.4	6.7	7.5	5.2(2.3-12)***	ns
Masturbation involving stimulating your anus.	37.0	14.3	13.2	3.8(1.7-8.5)**	ns
Masturbation involving insertion of objects into your rectum.	25.9	10.9	8.8	3.5(1.5-8.5)*	ns
Masturbation involving using an artificial vagina of any kind.	40.7	12.6	8.4	7.1(2.7-16)***	ns
Masturbation behaviors after age 18
Masturbation involving a vibrating device.	37.0	9.2	9.9	5.4(2.4-12)***	ns
Masturbation involving stimulating your anus.	44.4	10.9	15.6	4.5(2.1-9.8)***	ns
Masturbation involving insertion of objects into your rectum.	33.3	9.2	10.1	4.5(2.0-10)***	ns
Masturbation involving using an artificial vagina of any Kind.	25.9	8.4	6.6	4.8(2.0-12)**	ns

Note. ¹Each percent “no” can be found by subtraction. ²Each odds ratio shows the predicted increase in likelihood over controls of engaging in the behavior. ³A Bonferroni correction has already been applied to every p-value in this table: Each significance level was first Bonferroni corrected by multiplying by two: * = p < .05, ** = p < .01, and *** = p < .001.

Child Sexual Abuse by Female Perpetrators has a Deleterious Impact on an Adult Man's Sexual Adjustment with his Adult Partners

As mentioned above, the victims of SBI had significantly more problematic scores than either the control group or the CSA-AF group on the Sex-positive Complaints about Sex with Partner subscale. The participants who were victims of SBI had significantly more problematic scores on the Sexual Satisfaction scale than the CSA-AF group. Both victims of SBI and CSA-AF had significantly more problematic scores on the Conflicts scale than the control group. However, victims of CSA-AF had significantly less problematic scores on the Sexual Satisfaction scale than controls (Table 2). Victims of CSA-AF (but not victims of SBI) were more likely than controls to endorse Item 11, indicating that they had cheated on their spouse or long term partner by having sex with women (Table 7). Victims of SBI were more likely than controls to endorse Item 12, indicating that they had cheated on their spouse or long term partner by having sex with men (Table 7), and five of those six had their first same-sex experience prior to age 18. The SBI predictor was powerful enough (p < .05 without Bonferroni correction for entry) to be included in all eight of the multiple logistic regression equations predicting adult sexual behaviors with adult males listed in Table 7 (as the third most powerful predictor after CSA-AM and BBI), and victims of SBI were significantly more likely than controls to have engaged in four of those eight sexual behaviors even after applying the (4 times) Bonferroni correction. Male-male behavior before age 18 antedated the first instance of female-male behavior in only three SBI cases, and it occurred in the same year in only three cases, indicating that the tendency toward male-male behavior developed after the first instance of female-male behavior in most of the BBI cases in which it occurred. Victims of SBI were also more likely than controls to endorse Item 16, indicating that they had not discussed all of their childhood sexual experiences with their spouse or partner (Table 7). Victims of SBI were significantly more likely than controls to believe that sexual addiction could explain some of their sexual behaviors, and they were significantly more likely than controls to have sought treatment for sexual addiction.

The Effects on the Victims of SBI Differ from Those of CSA-AF

The victim of SBI group (but not victims of CSA-AF) was significantly more likely than controls to report being more distant from the perpetrator-sister (Table 7). Victims of SBI reported having engaged in four of the behaviors with female partners significantly fewer times than did victims of CSA-AF (Table 4). Victims of SBI reported having engaged in five behaviors with female partners at a significantly earlier age than did victims of CSA-AF (Table 5). Victims of SBI reported last having engaged in all seven of the behaviors with female partners at a significantly younger age than did victims of CSA-AF (Table 6). Being a victim of SBI was a significant predictor for endorsing seven of the first thirteen items in Table 7, but being a victim of CSA-AF was a significant predictor for only one of those thirteen items.

SBI Can Have Adverse Effects on the Brother-victim When his Participation is Voluntary and Also When his Participation is Coerced

Of the total of 27 SBI victims, 25 listed some or all of the SBI as voluntary, and seven listed some or all of the SBI as coerced by the sister. There were five of the 27 who listed the SBI under both categories. These data were encoded as two (voluntary and coerced) dummy variables coded “0” and “1” to serve as predictor variables; the overlap in five of the 27 cases resulted in some collinearity between the two predictors. Substitution of these two predictor variables for the single incest variable in the logistic regressions reported in Table 7 allowed us to test the relative predictive power of having participated in SBI voluntarily versus having been coerced by the sister while also adjusting for some participants having been victims of CSA-AF. These logistic regression analyses showed that having participated voluntarily in SBI was the more powerful predictor for endorsing feeling like damaged goods, having suffered psychological injury (although both were significant at step-0 in the logistic regression), having a listener react with horror and disgust when he tried to open up about his childhood sexual experience, not having discussed his childhood sexual experiences with a spouse or long-term partner because he felt that the partner might not handle it well, being more distant from the sister-perpetrator than from other siblings, and having participated in voluntary or coerced sex of any kind with a male partner under 18 before reaching age 18. In contrast, being the victim of coerced SBI was the more powerful predictor for being distant from both parents or distant from mother and close to father in high school, having adults that he had sexual experiences with as a child appear in his nightmares, and having children that he had sexual experiences with (as a child) appear in his nightmares (the odds ratio, 95% CI, and p-value after a 3-times Bonferroni correction were 39[3.9–384], p < .01 for coerced SBI vs. controls). Both voluntary participation and coerced participation were included as significant predictors in the logistic regression equation for predicting having undergone psychological treatment for childhood CSA. These results support the idea that either voluntary or coerced participation in SBI can have adverse effects on male-victims that last into adulthood.

DISCUSSION

To our knowledge, the present study was the first to systematically explore the effects that SBI and CSA-AF ultimately have on the male-victims in comparison to appropriate controls. Our results showed that SBI can be psychologically harmful to the male-victims. Furthermore, the present study has shown that harm to the male-victim can occur even when he believed that he was participating in the incest or CSA-AF voluntarily.

The findings from our study were consistent with harm to the male-victims of SBI being caused by at least five different mechanisms as discussed by others in women (e.g., Russell, 1986; Stroebel et al., 2012; Yates, 1982 with regard to FDI; Stroebel, O’Keefe, Griffee et al., 2013, with regard to SSI, and Stroebel, O’Keefe, Beard et al., 2013, with regard to BSI) and in men with regard to BBI (Beard et al., 2013).

1. Our data did provide statistically significant evidence for a tendency of SBI victims to have a large number of sexual partners after reaching adulthood and a tendency to cheat on their partners as adults by having sex with men, an effect similar to that observed in victims of BBI and CSA by adult men (Beard et al., 2013). Victims of SBI had significantly more problematic scores than either the control group or the CSA-AF group on the Sex-positive Complaints about Sex with Partner subscale, indicating that they did not believe that their long-term sex partners were effectively meeting their sexual needs. Furthermore, victims of SBI had significantly higher scores than controls on both the hypersexuality and risky sexual behaviors scales and all four subscales, indicating an increased interest in sex and an increased tendency to engage in risky sexual behaviors that had persisted into adulthood. These findings also were supported by the fact that being a victim of SBI was also a significant predictor for believing that sexual addiction could explain some of their sexual behaviors and also for their actually having sought treatment for sexual addiction.

2. Our data provided evidence that feeling harmed and damaged from shaming by hearing that they had engaged in harmful, forbidden sex with their sisters occurred sometimes.

3. SBI victims often did not discuss their childhood experiences with their partners once they became adults, but there was no statistically significant evidence from the sexual communication scale (Table 2) that they had not learned to talk about what they were feeling during sex or what they needed from their partners to enjoy themselves sexually even after they became adults.

4. As adults, 3.7% endorsed having experienced nightmares that featured their childhood child sexual partners.

5. Approximately 22% of the victims of SBI endorsed Item 18, indicating that they were distant (estranged) from the sister–perpetrator. Loss of attachment to the brother (in BSI) or the father (in FDI) results in an emotional cut-off (Caffaro & Conn-Caffaro, 2005; Rudd & Herzberger, 1999). In other research emotional cut-offs predicted poorer functioning in marriage and other relationships (Peleg, 2008; Skowron, Stanley, & Shapiro, 2009) and a greater risk for becoming a mother who maltreats her children (Skowron, Kozolowski, & Pincus, 2010). The victims of SBI identified in the present study seem to have been mostly spared from loss of attachment to the parents, but this may well be because the SBI was never brought to the attention of the authorities. Removal from the family, which sometimes happens upon discovery when the authorities become involved (Sheineberg & Fraenkel, 2001), could produce very different results.

For male SBI victims who are still children or adolescents at the time of treatment, it is also important to recognize that some SBI victims (like FDI victims, e.g., Stroebel et al., 2012; Yates, 1982; and BSI victims, e.g., Stroebel, O’Keefe, Beard et al., 2013) have been eroticized by the incest experience. Furthermore, our data showed that victims of SBI, like female victims of FDI, BSI, and CSA by adult males, were at risk for subsequent involvement in sexual behaviors with male partners and other female partners. All such victims should receive birth-control information and be provided with access to birth-control as part of therapy, and they should also be instructed in safe-sex techniques as applied to both male and female partners. As in FDI, family systems therapy for SBI potentially provides a vehicle for maintaining the intact family and existing ties between family members (Maddock & Larson, 1995; Sheinberg & Fraenkel, 2001), but removing either the male SBI victim or his sister from the family all but guarantees the creation and perpetuation of one or more emotional cut-offs between the SBI victim, his parents, and his sister, as seen for removal of the father in FDI cases (Maddock & Larson, 1995).

It is now clear that early experiences with sexual partners within the family or outside of the family can lead to a lifelong increased interest in sex that can be difficult for the victims to control (Beard et al, 2013; Stroebel et al., 2012; Stroebel, O’Keefe, Beard et al., 2013; Stroebel, O’Keefe, Griffee et al., 2013; Yates, 1982), and that leads to the symptoms of sexual addiction. The origins of this increased interest in sex and the origins of bisexual or same-sex sexual orientations (Beard et al., 2013) as well as the origins of many of the powerful urges to engage in behaviors such as exhibitionism (Swindell et al., 2011) or to use objects sexually (O’Keefe et al., 2009; Stroebel et al., 2010) can be explained as arising from early childhood experiences through the synergistic actions of critical period learning, sexual imprinting, and conditioning (for reviews see Hoffman, 2012; Pfaus et al., 2012). Obtaining a careful history of early sexual experiences in clients seeking help because of symptoms of sexual addiction or paraphilias may provide insight into the origins of the presenting symptomatology.

The increase in same-sex and bisexual orientations and behaviors in adult survivors of sister-brother incest would at first glance appear to be paradoxical since conditioning resulting from sexual experiences with the sister would be expected to lead to a heterosexual orientation (Beard et al., 2013, Bickham et al, 2013, Stroebel et al., 2013; for reviews see Hoffman, 2012; Pfaus et al., 2012). However, as shown by the data from the logistic and multiple linear regressions in the present article, the mechanism leading to the adult same-sex or bisexual orientations and behaviors involves two steps. The first step occurs in childhood or adolescence when the increased interest in sex increases the chance that the victim of SBI will become involved in sexual experiences with other partners of either sex. The 13 (48.1%, Table 7) victims of SBI who happened (more or less randomly) to become involved with other males before reaching 18 years of age at a median age of eight (Table 8) were the ones who subsequently manifested adult same-sex or bisexual orientations and behaviors—as a result of the second step, critical period learning and sexual imprinting produced by the childhood or adolescent experiences with male partners working in concert with Pavlovian conditioning and operant conditioning (Beard et al., 2013; Bickham et al., 2007; Robinett, 2012; Stroebel, O’Keefe, Griffee et al., 2013; for reviews see Hoffman, 2012; Pfaus et al., 2012). This was demonstrated in the present study by the powerful predictive effect of the 0/1 dummy variable coding for sexual behavior with males under the age of 18 before age 18 as a predictor for having a sexual experience with another adult male as an adult and also for the score on the adult male-male sexual orientation scale.

The powerful effect of same-sex sibling incest as a predictor of adult same-sex orientation and of same-sex CSA by adult males in our participants reported by Beard et al. (2013) and same-sex orientations in victims of sister-sister incest (Stroebel et al., 2013) provide critical period learning, sexual imprinting, and conditioning explanations for three phenomena used in the past to support claims that there is a genetic basis or other biological basis for same-sex orientations: concordance of sexual orientations between twins (see Blanchard, 2001; Dawood, Bailey, & Martin, 2009; and Mustanski, Chivers, & Bailey, 2002 for reviews), an increase in same-sex orientations in men with older brothers (see Blanchard, 2001; Dawood et al., 2009; and Mustanski et al., 2002 for reviews), and earlier puberty in gay men than in heterosexual men (Bogaert & Friesen, 2002; Bogaert, Friesen, & Klentrou; 2002; Saghir & Robins, 1973; Savin-Williams, 1995). Concordance of sexual orientations among identical twins (e.g., Blanchard, 2001; Dawood, et al., 2009; Kirk, Bailey, Dunne, & Martin, 2000; and Mustanski et al., 2002 for reviews) is easily explained by the high likelihood of incest between the twins (King & McDonald, 1992) and the effect of same-sex incest on adult orientation (Beard et al., 2013). The higher incidence of same-sex orientations in men with older brothers (see Blanchard, 2001 and Mustanski et al., 2002 for reviews) is also easily explained by incest between the two brothers having a more profound effect on the younger brother because of critical period learning (Beard et al., 2013) and by other environmental factors (McConaghy et al., 2006). As shown by results from the present study, the earlier onset of puberty in gay men is easily explained by a stronger early sex drive (driven by rising levels of testosterone) and by their sexual behaviors with the only sexual partners that young males have easy access to, other males.

Furthermore, the participants in our study who were victims of SBI and who also had early sexual experiences with males had a high interest in sex with both males and females as adults, a finding consistent with the idea that their early experiences produced coexisting same-sex and heterosexual preferences as described by Bickham et al. (2007) in women. Our findings definitely did not provide any evidence that could be interpreted as supporting a genetic basis for sexual orientation, because many victims of SBI subsequently engaged in early sexual experiences with male partners, and others became victims of SBI subsequent to or in the same year as early sexual experiences with male partners. Additionally, the adult sexual orientations of those participants who were victims of SBI and who also had early experience with male partners reflected conditioning of both male-male and heterosexual orientations, a finding consistent with the idea that both co-existing orientations arose from conditioning occurring in the critical period (Beard et al., 2013) and the idea that male-male and male-female sexual orientations are orthogonal (Bickham et al., 2007).

The negative regression coefficients of variables and cross products related to sexual behaviors with female partners as predictors of an adult male-male orientation as measured by the M-MSOS score (Table 9) appeared to reflect counter-conditioning in those with early experiences with male partners because there was no evidence provided by the logistic regressions for inhibition of early male-male experiences by sexual experiences of any kind with female partners of any age before reaching 18 years of age. While it is generally accepted that that counter-conditioning and other methods directed at changing the sexual orientations of adults are not effective when they have been applied to adult men with established same-sex orientations (Beckstead, 2012), to our knowledge, ours is the first study to provide evidence of counter-conditioning that occurred during the critical-period for learning sexual preferences and more-or-less contemporaneously with same-sex conditioning trials. Based on data from the present study, that of Beard et al, (2013), and that of Stroebel, et al. (2013), same-sex and heterosexual conditioning experiences during the critical period for learning sexual preferences appear to explain a major portion of the development of adult sexual orientations and also the immutability of those sexual preferences once adulthood has been reached. Despite the strong evidence for conditioning and counter conditioning during the critical period provided by the present study and those of Beard et al, (2013), and Stroebel et al. (2013), our results neither suggest that counterconditioning of sexual preferences will work in adults nor do they rule out the possibility that genetic factors may alter the chance of developing an adult same-sex orientation. It is highly likely that any such genetic effects would operate indirectly, say by influencing the age of puberty or obedience to rules and thus, indirectly, alter the chance of having sexual experiences with male or female partners during the critical period for learning sexual preferences (for reviews see Blanchard, 2001; Dawood et al., 2009; and Mustanski et al., 2002).

Limitations to the Study

The limitations of this study have already been discussed in Beard et al. (2013). Our findings provide important information about the impact of both voluntary and coerced SBI on the brothers. Future studies are needed to test for differences in the effects of voluntary and coerced SBI on the brothers and to identify risk factors for SBI.

APPENDIX A

(©S-SAPE, LLC. Reproduced by permission of S-SAPE, LLC, 2002, P.O. Box 11081, Charleston, WV 25339. Permission to reuse must be obtained by the rightsholder.)

SEXUAL BEHAVIOR SCREEN

The screen displayed each behavior item (one at a time), detailing not only the behavior but also that it was voluntary or coerced. Participants only viewed items appropriate to their sex. Each item specified the age of the respondent at the time, the age-differential category, and sex of the partner. The questions were presented in a multi-tiered hierarchically structured format. Items (1) and (2) below represent second-tier screening questions that only allowed access to third-tier questions if they were answered affirmatively (Haning et al., 2007). Item numbers (1) and (2) are presented below as examples of a total of 16 items describing behaviors that described CSA by an adult female.

• Item 1. “Your age range: 1–17 years; Behavior: Sexual experimentation of any kind with a female age 18 or older and more than 4 years older than yourself. Give your best guess for numbers—don't get hung up on being precise!”

• Item 2. “Your age range: 1–17 years; Behavior: Coerced sexual situations of any kind with a female age 18 or older and more than 4 years older than yourself. Give your best guess for numbers—don't get hung up on being precise!”

In a 15-minute talking PowerPoint orientation that participants viewed immediately before study participation, they were instructed to list behaviors as voluntary if they thought that it was voluntary at the time that it occurred even though they were below the age of legal consent at the time that the behavior occurred. They were informed that each behavior described in the voluntary format would also appear (later) in the coerced format. They were also informed that for the purposes of study participation “coerced” encompassed physical force, blackmail, age, and power differentials that made participation feel coerced rather than voluntary.

The subsequent third-tier items describing behaviors that constituted CSA by an adult female were constructed by the computer program by substituting the following 7 phrases (labeled “b” through “h” for the behavior phrase in items (1) and (2).

1. “of any kind”

2. “involving touching your female partner's breasts”

3. “involving the female partner looking at your genitals”

4. “involving looking at your female partner's genitals”

5. “involving touching your female partner's genitals”

6. “involving having the female partner touch your genitals”

7. “involving inserting of your penis into your female partner's vagina”

8. Your age range: 18–99 years; Behavior: Sexual relations of any kind with a female age 18 or older. Give your best guess for numbers - don't get hung up on being precise!

9. “involving intravaginal ejaculation”

10. “involving reaching orgasm”

11. “involving ejaculating in your male partner's rectum”

12. “involving ejaculation as a result of oral stimulation of your penis”

13. “involving reaching orgasm as a result of manual stimulation of your penis”

14. “involving bringing your male partner to orgasm by stimulating his penis with your mouth”

15. “involving bringing your male partner to orgasm by stimulating his penis with your hand”

16. “involving sexual relations with a male prostitute”

The unchanged items (A) through (H) were substituted into item (1). Similar substitutions were made for each phrase into item (2) except that the phrase “the coercing female” was substituted for “your female partner” whenever it occurred. Items (I)–(Q) were only paired with age ranges indicating that both partners were at least 18 years old when the behavior occurred. Item (I) was similar for male and female partners except for substitution of the appropriate sex name. Item (J) always specified female partners, and Items (K)–(Q) always specified male partners.

Sexual Behavior Sub-items

The following sub-item variables were the actual prompts used in the sexual behavior screen to obtain the data used in this research.

1. “Did you ever engage in this behavior in this age range? (No/Yes coded 0/1)

2. “Number of partners:”

3. “On about how many occasions did you engage in this behavior?”

4. and

5. “What were the earliest and latest ages in the “(applicable age range)” age interval that you engaged in this behavior?”

6. “Was mother involved” or “Was father involved” These questions were only asked when the partner described in the item was more than four years older and over age 18 and of the female sex (for mother) or the male sex (for father), respectively. (No/Yes coded 0/1)

7. “Was sister involved” (for female partners) or “Was brother involved” (for male partners) was asked for all partner-age categories (No/Yes coded 0/1).

Items 5, 6 and 11–17 (below) were presented as agree/disagree and coded 1/0, while items 7–10 and 18–20 were presented as multiple-choice.

• Item 5. “My childhood sexual experiences left me feeling like damaged goods, that my value had been diminished.”

• Item 6. “I have suffered serious psychological injury as a result of one or more of my childhood sexual experiences.”

• Item 7. “The best way to describe the feelings of closeness that I had toward my parents as a child of high school age is: (a) I felt very distant and estranged from both parents. (b) I felt close to my mother but distant from my father. (c) I felt close to my father but distant from my mother. (d) I felt close to both parents but somewhat closer to my mother. (e) I felt close to both parents but somewhat closer to my father.”

• Item 9. “The best way to describe my relationships with other members of my family of origin is: (a) I have never had long-term anger at or estrangement from either parent or any sibling, and I have good relationships with all members of my family of origin today. (b) I still have long-term anger at or I am estranged from one or more of my parents or siblings. (c) Although I had long-term anger at or was estranged from one or more of my parents or siblings, we have worked through our issues and we now have good relationships.”

For item 9, answer (b) was coded as “1” and all other answers were coded as “0” to create a binary variable.

• Item 10. “The best way to describe my adult dreams about adults who I had sexual experience (of any sort) with as a child is: (a) I still find that one or more of the adults that I had childhood sexual experiences with appear in dreams linked with sexual arousal, and I am comfortable with that. (b) I still find that one or more of the adults that I had childhood sexual experiences with appear in dreams linked with sexual arousal, and I am uncomfortable with that. (c) While I had childhood sexual experiences with one or more adults and they appeared in dreams linked with sexual arousal in the past, they have not appeared in dreams for many years. (d) The only way that the adult(s) that I had sexual experiences with as a child have ever appeared in any of my dreams was in nightmares and the feeling was terror or horror. (e) None of the above: I either had no childhood sexual experiences with adults or I had no dreams about them linked to either sexual response or nightmares.”

For item 10, answer (d) was coded as “1” and all other answers were coded as “0” to create a binary variable.

• Item 11. I have cheated on my spouse or long-term partner by having sex with women during our relationship.

• Item 12. “I have cheated on my spouse or long-term partner by having sex with men during our relationship.”

• Item 13. “I have engaged in sex for the specific purpose of obtaining money, drugs, or other goods in exchange for sex.”

• Item 14. “I have undergone psychological treatment for my childhood sexual abuse.”

• Item 15. “When I tried to open up with another person about my childhood sexual experience, he/she reacted with horror and disgust.”

• Item 16. “I have not discussed all of my childhood sexual experience with my spouse or long-term partner because I felt that he/she might not handle it well.

• Item 17. “I have fathered an unplanned pregnancy.”

• Item 18. The best way to describe my adult relationships with my sister(s) that I engaged in childhood sexual experimentation with is: (a) I am closer to that (those) sister(s) than to other siblings. (b) I am more distant from that (those) sister(s) than from other siblings. (c) I cannot say that childhood sexual experimentation made any difference in my being closer to or further from my siblings. (d) I never experimented sexually with any sisters.

Answer (b) was coded “1” and all other answers were coded “0” to create a binary variable.

• Item 19. Item 19 was identical to Item 10 except that the word “adults” was replaced with the word “children.”

APPENDIX B

(©S-SAPE, LLC. Reproduced by permission of S-SAPE, LLC, 2002, P.O. Box 11081, Charleston, WV 25339. Permission to reuse must be obtained by the rightsholder.)

Factor Analysis of the Sexual Satisfaction Scale in 1,178 Men

			Factor
Scale Item Wording	#	R^1	No.^3	Loading
1. Our sexual interaction greatly enhances our over-all relationship.^2	1		1	.740
2. My partner uses sexual behaviors that I enjoy.	2		1	.849
3. I really think that our sexual relationship is sensational.	3		1	.865
4. My spouse or long-term partner shames me for some of the sexual behaviors that I want to try with him/her.	4	R	3	.554
5. My spouse or long-term partner criticizes me when we are having sex.	5	R	3	.441
6. My spouse or long-term partner does not satiate my sexual appetite.	6	R	3	.697
7. I perform sex-acts that I don't like to please my spouse or long-term partner sexually.	7	R	2	.348
8. My spouse or long-term partner actively uses certain ways to avoid sexual relations with me.	8	R	3	.744
9. My spouse or long-term partner is receptive to introducing new and innovative sex-acts into our sexual relationship.	9		1	.621
10. My spouse or long-term partner goes out of his/her way to please me sexually.	10		1	.722
11. My spouse or long-term partner does not seem to want sex when I am in the mood for it.	11	R	3	.788
12. My spouse or long-term partner is very responsive to my sexual requirements and cravings.	12		1	.797
13. When we have sex, my spouse or long-term partner is too rough-and-tumble or mean.	13	R	2	.574
14. Having sex with my spouse or long-term partner is a tedious duty for me.	14	R	2	.619
15. My sexual relationship with my spouse or long-term partner is boring and monotonous.	15	R	3	.631
16. I believe that I please my spouse or long-term partner sexually.	16		1	.822
17. It is easy for me to become aroused sexually by my spouse or long-term partner.	17		1	.824
18. I think that sex with my spouse or long-term partner is filthy and revolting.	18	R	2	.489
19. My spouse or long-term partner relishes our sexual relationship.	19		1	.747
20. When my spouse or long-term partner and I have sex it is finished too quickly.	20	R	3	.536
21. Our sexual relationship is very arousing to me.	21		1	.895
22. I believe that sex is a normal part of our over-all relationship.	22		1	.811
23. I find my spouse or long-term partner to be very sexually arousing.	23		1	.860
24. I believe that my sexual relationship with my spouse or long-term partner is deficient in essential ingredients.	24	R	3	509
25. My spouse or long-term partner and I both have fun at sex.	25		1	.893
26. I believe that my spouse or long-term partner desires too much sex.	26	R	2	.711
27. I attempt to avoid sexual relations with my spouse or long-term partner.	27	R	2	.575
28. My spouse or long-term partner thinks about sex excessively.	28	R	2	.624
29. My spouse or long-term partner is a great sex companion.	29		1	.879

Note. ¹R indicates that the item is reverse-scored.²Choices for answers: (1) less than 10% of the time (2) about 25% of the time (3) about 50% of the time (4) about 75% of the time (5) more than 90% of the time.³The 29-item SRI scale includes all 29 items, and factor analysis showed that it is comprised of three subscales as indicated by factor numbers 1–3: 1) the 14-item Sex-positive and Partner-affirming Statements subscale, 2) the 7-item Sex-negative Statements about Sex with the Partner subscale, and 3) the 8-item Sex-positive Complaints about Sex with Partner subscale. The 27-item sexual satisfaction scale (Haning, 2005, Haning et al., 2007) did not include item-26 or item-28.