Young Adult Sibling Relations: The Effects of Perceived Parental Favoritism and Narcissism

ABSTRACT

The present study examined predictors of siblings’ relations in 202 young adults (aged 21–32 years), who completed the Adult Sibling Relationship Questionnaire and the Narcissistic Personality Inventory. Results indicate that warmth between siblings is explained by gender (with women feeling closer), perceived paternal favoritism, low levels of narcissism, and an interaction suggesting that paternal favoritism moderates the link between narcissism and sibling warmth. Conflict between siblings was explained by gender (sisters), age, parental favoritism, high levels of narcissism, extreme levels of similarity or dissimilarity between siblings, and interactions indicating that older age is a predictor of conflict between siblings among women but not among men. The impact of parental favoritism and narcissism on sibling relationships in young adulthood was discussed.

Keywords:

• narcissism
• parental favoritism
• siblings
• similarity
• young adulthood

THE PRESENT STUDY EXAMINED (a) the impact of the perception of parental favoritism of one sibling over another, narcissism, and the perception of similarity with the sibling on siblings’ warmth and conflict in emerging adulthood and (b) the impact of gender on siblings’ relations. Sibling relationships are the most enduring of family relationships. These relationships begin in early childhood and continue into old age. The course of sibling relationships is characterized by warmth and by siblings’ involvement in each other's lives, as well as by conflict and rivalry, and are often best described as emotionally ambivalent (Bedford, 1989a; Deater-Deckard, Dunn, & Lussier, 2002). Although the nature of these relationships changes over time, siblings remain important figures throughout each others’ lives (Cicirelli, 1995; Schulman, 1999).

The vast majority of sibling research has focused on relationships in childhood, sibling attachments, rivalry, birth-order, and other related topics (e.g., Dunn, 1983; Furman & Buhrmester, 1985; Kennedy & Kramer, 2008; Stocker, Dunn, & Plomin, 1989). More recently, research has been conducted on elderly siblings (Bedford, 1989b; Schulman, 1999) and on sibling relations in late adulthood (Bedford, 1998c). Several studies have focused on how sibling relationships affect individuals during middle adulthood, observing that siblings provide companionship, emotional support, and occasionally financial support for each other. They can usually be relied upon for help during times of crisis and typically cooperate with each other in the care for their elderly parents (Cicirelli, 1995; Goetting, 1986; Milevsky, 2005; Stewart, Verbrugge, & Beilfuss, 1998).

The literature on sibling relationships in young adulthood is still more scant (White, 2001), and less is known about the processes and variables influencing it. The lack of an integrated picture of the developmental course of sibling relationships was pointed out by Cicirelli (1995), who noted that the greatest gap in knowledge relates to the period of young adulthood. At this time, sibling relationships undergo developmental transformations: Differences between siblings are less salient than in childhood, and therefore they may have more egalitarian relationships (Stocker, Lanthier, & Furman, 1997). During this phase of the lifespan, siblings are also likely to vary in the affectionate features of their relationships. Some, siblings, but not all, may provide support and affection for each other as they move through normative developmental transitions such as marriage, raising a family, developing a career, and, in some cases, caring for aging parents (Stocker, Lanthier, & Furman, 1997). Nevertheless, Stocker et al.'s study (1997) indicated that adults experience feelings of warmth as well as conflict or rivalry toward their siblings, and continue to be concerned over parental attention, even though few continue to reside with their parents.

While the literature describes the devastating consequences of the perception of parental unequal treatment on an individual's sense of self-worth and personality (e.g., Rauer & Volling, 2007), the correlates between features of sibling relationships and narcissism (a personality variable with profound impact on interpersonal relations) have not been investigated so far. Moreover, in young adulthood—a developmental stage of personality formalization and consolidation—siblings in the process of self-differentiation often examine the similarities and differences between them (Vivona, 2007). However, how such a similarity or dissimilarity affects their relationships is yet unknown.

This study therefore investigated the role of the perception of parental unequal treatment, narcissism, and sense of similarity or dissimilarity in perceptions of warmth and conflict between siblings, which we assume to be of great importance not only in childhood but also in young adulthood (Scharf, Shulman, & Avigad-Spitz, 2005; Spitze & Trent, 2006). This is considered from a developmental perspective in which parental differential treatment of siblings is seen as shaping narcissistic traits and thus sibling relationships themselves. In addition, the process of developing one's autonomy and identity as an independent and differentiated adult is also affected by perceptions of how one resembles or differs from others in the family unit; identification with and differentiation from a sibling appear to be crucial for identity formation (Weaver, Coleman, & Ganong, 2003). Hence, perceptions of sameness and difference are the hallmarks of sibling relationships and are indispensable to them (Schulman, 1999). Finally, gender has been perceived to be one of the key factors influencing the nature of adult sibling relations. Women are described as closer to their siblings than men are since they tend to be kin-keepers and tend to emotional closeness. However, other results have been varied or inconclusive as to gender differences (e.g., Spitze & Trent, 2006). We initially discuss sibling relationships in young adulthood (taking gender into account as well), followed by a review of the links between parental unequal treatment, narcissism, and siblings relationships.

Sibling Relationships in Young Adulthood

Arnett (2000) highlights developmental tasks such as autonomy, identity exploration, and transition into adult roles as unique to young adulthood. These role changes have significant impact on family relations as well as sibling relationships.

Stocker, Lanthier, and Furman (1997) developed the Adult Sibling Relationship Questionnaire (ASRQ), which focuses on adults’ perceptions of sibling relationships along three dimensions: warmth, conflict, and rivalry (the average age of participants was 21 years). Their investigation of the associations between family variables and sibling relationships indicated that mixed-gender siblings report less conflict in their relationships than siblings of the same gender; women report more rivalry in their sibling relationships than men; and participants had both warmer and more conflicted relationships with their sisters than with their brothers. Stewart, Verbrugge, and Beilfuss (1998), who adopted existing sibling relationship categories from the literature on children and the elderly (including intimate, congenial, loyal, apathetic, and hostile), classified sibling relationships in young and middle adulthood (between the ages of 17 and 56 years) into four types: caretaker, buddy, casual, and loyal. Their results showed that the caretaker and buddy types of relationship could be clustered into the warmth domain of Stocker, Lanthier, and Furman's (1997) questionnaire, whereas casual siblings would resolve their sibling rivalry to a degree sufficient to establish a loyal but apathetic relationship; and in those cases where rivalry resulted in interpersonal conflict, the siblings may maintain hostile relationships. Based on a national survey of families and households among 13,007 respondents over 19 years of age, Spitze and Trent (2006) reported that women were more likely than men to report getting along well with their siblings, and that their siblings were among their closest friends. However, Wu Shortt and Gottman (1997) found no evidence that sibling closeness could be explained by gender or other family variables, in their sample participants between the ages of 18 and 30 years.

Roggio (2000) developed the Lifespan Sibling Relationships Scale, which showed a high positive correlation with the Warmth subscale of the ASRQ. Her study, among 711 students with a mean age of 23.5 years, indicated gender differences whereby women report more positive emotions toward, and more frequent and positive behavioral interactions with siblings. Her participants also reported more positive feelings and more positive interactions with sisters than with brothers. Based on a large cohort, Roggio (2006) recently found that the eldest siblings in the family report less positive attitudes toward a younger sibling.

Until recently, studies of adult sibling relationships did not explore much beyond family constellation variables (e.g., effects of birth order, age, and gender). Less is known about the association between the development of personality traits and preferential treatment by parents. The present study examined the link between parental unequal treatment and narcissism, on the one hand, and adult sibling relationships, on the other.

Unequal Parental Treatment, Narcissism, and Sibling Relationships

One of the factors that have been identified as influential in determining the nature of sibling relationships is the individual's experiences of differential parenting practices within the family (Gilbert & Gerlsma, 1999; Suitor et al., 2006). Differential parenting refers to differences in how parents behave toward one child relative to their behavior toward other children in the family. Differential parenting that is perceived by children as legitimate, based on the different needs of the children and responsive to the developmental differences between them, may not have the same emotional sequelae as parental behavior that is perceived as unfair and consistently “one-sided.” These latter parenting practices can more readily be construed as parental favoritism. It is the child's experience of differential parenting practices as unfair and inequitable that exacerbates the adverse effects of differential parenting on the quality of the sibling relationship. Parents’ differential treatment of siblings has been hypothesized to contribute to variations in the quality of sibling relationships and has been conjectured to create negativity in their relationship by inducing feelings of rivalry, anger, and mistrust (Gilbert & Gerlsma, 1999; Rauer & Volling, 2007). Garcia, Shaw, Winslow, and Yaggi (2000) state that being the nonpreferred child increases that child's conflict with siblings during childhood.

Boll, Ferring, and Filipp (2003), who studied 1,020 adults between the ages of 40 and 54 years, reported that an individual's experienced relationship with a sibling was best when both were treated equally and diminished with increasing favoritism or disfavoritism. The favored sibling would be the one likely to experience guilt toward or contempt for the disfavored brother or sister who, in turn, is likely to experience feelings of anger, resentment, and jealously toward the favored sibling (Angel, 2006; Brody, 1998). Disparities in parents’ affection for and warmth toward different children in the family, and differences in how restrictive and punitive parents are toward each child, have been shown to undermine the quality of the sibling relationship during childhood and adolescence and to provoke hostile, coercive, and frequent conflict between siblings (Boer, Goedhart, & Treffers 1992; Brody, Stoneman, & McCoy, 1992; Feinberg, Reiss, Neiderhiser, & Hetherington, 2005; McHale, Crouter, & McGuire, 1995; McHale et al., 2000). Rauer and Volling (2007), who studied 200 young adults aged 18–22 years, reported that parental differential affection was strongly related to feelings of jealousy toward one's sibling.

Perceptions of being treated unfairly by the parent and of being the disfavored child may accompany the individual into adolescence and adulthood. Studies regarding sibling relationships in adolescence have been described as being more negative when parents’ behaviors are directed unequally toward their children (Brody, Stoneman, & McCoy, 1992, 1994; McHale, Crouter, McGuire, & Updegraff, 1995). Low self-esteem, behavioral problems, or unsatisfactory sibling relationships may be the consequences of receiving less parental affection or more negative discipline than one's sibling (Boll, Ferring, & Filipp, 2003; Brody, 1998; Shebloski, Conger, & Widaman, 2005). Research indicates that unequal parental treatment affects siblings’ psychological functioning and causes their relationships (in young adulthood) to be more conflictual (Stocker et al., 1997).

The present study is anchored in an object-relations family approach that assumes that in young adulthood, sibling relations are derived from the internal representations of the experiences of each sibling with the parents and the perception of differential parental care and attitude toward each sibling. Early interactions with parents and siblings are viewed as weighty factors with regard to the formation of later adult personality, which in turn affects subsequent interpersonal relations (Akhtar & Kramer, 1999; Colonna & Newman, 1983; Neborsky, 1997). These family-based internalized experiences are manifested in the everyday interactions that take place between siblings in young adulthood (Charles, 1999; Rauer & Volling, 2007).

Experiencing parents’ differential treatment of siblings affects their perceptions of themselves. Sheehan and Noller (2002) argued that differences in parental differential treatment explain adolescents’ individual differences in perceptions of self and others. When parental favoritism is perceived, the nonfavored child may often feel inferior, angry, and depressed, as well as unattractive and incompetent. However, the favored child may often feel both positive (e.g., greater security and adoration) and negative (e.g., sibling jealousy and greater obligation to parents) consequences associated with parental favoritism. Thus, parental favoritism appears to be related to one's self-perception, whether one is the favored child or the nonfavored child and to be pathogenic for parents and children alike (as found among college students; Zervas & Sherman, 1994).

While previous research has shown associations between parental differential treatment and sibling conflict, the role of narcissism has not been examined. Narcissistic features are ascribed to rejecting parents and the child's subsequent feelings of abandonment or to constant overvaluation that is not based on any objective reality (Morf & Rhodewalt, 2001). Perceptions of unequal parental treatment can be associated with narcissistic injury and feelings of inferiority on the one hand or narcissistic grandiosity on the other. Being a special and preferred child in the family might instill grandiosity and a sense of entitlement (Bishop & Lane, 2002; Weise & Tuber, 2004), whereas being the nonpreferred child creates narcissistic vulnerability, due to a sense of unworthiness, of being unloved, and of feelings of envy, which in turn affect sibling relationships (Angel, 2006; Brody, 1998). The grandiose narcissistic individual is more likely to regulate self-esteem through overt self-enhancement, denial of weaknesses, intimidating demands of entitlement, consistent anger about unmet expectations, and devaluation of people who threaten his or her self-esteem (Dickinson & Pincus, 2003). The vulnerable subtype, in an attempt to fill the void in his adult relationships left over from childhood and to restore injured self-esteem, seeks reassurance; this type strives to allay a gnawing concern of inadequacy and is extremely sensitive to personal slights and criticism (Morf & Rhodewalt, 2001). The disavowal of the disappointments sustained by their covert grandiosity and expectations of entitlement leads them to brewing anger and hostile outbursts, which are followed by an experience of shame and depression. Vulnerable narcissistic individuals experience much greater anxiety in developing relationships with others because of the tenuous nature of their self-esteem (Dickinson & Pincus, 2003). We hypothesized that these narcissistic features would manifest in sibling relationships that might accompany the siblings into adulthood.

One might argue that whether parents treat their children differentially in adulthood is no longer an important issue because adult children usually have separated from their parents and have acquired functional and residential independence (Lawton, Silverstein, & Bengston, 1994). Yet there are reasons to believe that parental differential treatment continues to be an important issue in later life, given that there are a variety of occasions on which parents generally interact with their adult children and potentially behave differently toward them (Boll, Ferring, & Filipp, 2003).

Similarity and Sibling Relationships

Research on siblings’ similarity is only in its initial stages, and findings as to its effects on sibling relationships are as yet ambiguous. It is unclear whether similarity promotes fusion or whether siblings attain differentiation or choose their “niche” through conflict and dissimilarity (Feinberg et al., 2005; Jenkins et al., 2005). Hoffman (1991) suggests that dissimilarity is not surprising, considering the variety in objective and subjective family experiences because of birth order, age differences, gender, genetics, and idiosyncratic experiences. Whiteman, McHale, and Crouter (2007) identified three patterns in adolescents’ siblings’ relations with reference to sibling similarities and differences: (a) influence and competition—the second-born sibling try to be like an older sibling; (b) the younger siblings try to be different, trying not to be like, and not competing with their older siblings; and (c) “deidentification” and a wish to become different from one's brothers and sisters, which reduces sibling rivalry and competition. Vivona (2007), from a psychoanalytic perspective, claims that to maintain warm and close relationships with a sibling throughout life, one has to find one's unique place in a world of similar others. This challenge is fraught with conflict and ambivalence; its resolution may be accomplished through a process of differentiation, an active and unconscious process of identity development whereby a child amplifies differences from siblings and minimizes similarities. On the one hand, differentiation from siblings serves to mitigate interpersonal rivalry and to ease internal conflict associated with parental differential treatment and envy toward the siblings. On the other hand, similarity is often found to be a positive influence on personal relationships. Having similar personalities may lead to compatible interests and instill a sense of belonging and reassurance (Hoffman, 1991).

The Present Study

The purpose of the present study was to assess the variables influencing sibling warmth and conflict in emerging adulthood. Based on the preceding literature review, we assumed that family experiences such as being favored or disfavored by the parents, narcissism, and the perception of similarity with the sibling were likely to affect sibling relationships.

The first goal of this study was therefore to assess the link between perception of parental favoritism or disfavoritism and narcissistic personality traits and their association to sibling relationships in terms of warmth and conflict. It was hypothesized that the extent to which the parent favored or disfavored one sibling (the subject) over the other would be negatively associated with the relationship between the siblings and that this kind of parental unequal treatment would moderate the link between narcissism and sibling relations. We also postulated that a high degree of narcissism would be a hindrance to sibling warmth and would contribute to conflictual relationships.

The second goal of the study was to assess the contribution of perceptions of similarity or dissimilarity between siblings to the nature of their relationship. Similarity is often found to be a positive influence on personal relationships. Having similar personalities may lead to compatible interests and instill a sense of belonging and reassurance. As already mentioned, similarity may promote differentiation and evoke conflicts on one hand or has a positive effect on siblings’ relations on the other hand (Hoffman, 1991). The present study will examine the contribution of various levels of similarity to sibling relationships.

Finally, it has already been mentioned that studies have yielded contradictory findings regarding the effects of family structure variables (e.g., gender) on sibling relationships. Accordingly, the third goal of the study was to examine the influence of gender on warmth and conflict between siblings as well.

Method

Participants

Participants were 202 students aged 21–32 years (M = 26.67 years; SD = 6.29 years). Of these, 62.2% were women, and 37.8% were men. Participants were drawn from three academic institutes in central Israel and included undergraduate and graduate students and thus were predominantly from the middle class or the upper-middle class. Of the participants, 69% reported their economic status as “good”,” 12% reported it as “very good,” and 19% reported a “low” economic status. Of the participants, 47% were married, of whom 18% had one child, and 7% had two children.

Questionnaires were filled out voluntarily. After an explanation of the study objectives, participants gave their verbal consent to participate. For the purpose of the study, participants were asked to choose one of their siblings as their reference. They were instructed to describe the relationship with the sibling that had the “greatest impact on your life, positive or negative.” The chosen siblings’ ages ranged from 16 to 39 years (M = 27.14 years; SD = 8.21 years). Of the women in the study, 42% chose a brother, and 58% chose a sister. Among the men in the study, 47% chose a brother, and 53% chose a sister. In all, 54% of the men and 45% of the women chose an older sibling. No significant differences were found between men and women in the gender of the chosen sibling (χ² = .25; df = 1; p = .617) or in the choice of a younger sibling versus an older sibling (χ² = .65; df = 1; p = .53). All participants chose a biological sibling as the target sibling, and none chose a twin.

The majority of the participants (57.3%) had one sibling, 24.5% had two siblings, 16.5% had three siblings, and 1.7% had four siblings. A majority of the participants (34.2%) were the first- or second-born (35.2%) child in their families, and the rest were the third (19.1%), fourth (7.3%), or fifth (4.2%) child in the family.

Instruments

Adult Sibling Relationship Questionnaire

The Adult Sibling Relationship Questionnaire (ASRQ; Stocker, Lanthier, & Furman, 1997) assesses features of sibling relationships in young adulthood and beyond. Participants are asked to relate to one of their siblings that had the “greatest impact on your life, positive or negative” (in case there are more than two in the family) and rate to what extent various behaviors and feelings occur in their relationship.

The questionnaire consists of 81 items comprising three factors: warmth (closeness between siblings), conflict, and rivalry (parental favoritism or disfavoritism). For all ASRQ items (except rivalry), participants rate how characteristic each item is of themselves and of their sibling, using Likert scales ranging from hardly at all (1) to very much (5), higher scores indicating more warmth or conflict exists between siblings, depending on the question. Maternal and paternal rivalry items (reflecting perceptions of unequal parental treatment) are rated on a 5-point Likert scale (5 = participant is usually favored, 1 = sibling is usually favored).

In this study, a very high correlation was found between participants’ view of the relationship and their perception of the sibling's view of the relationships (Warmth r = .92; Conflict r = .90; Parental favoritism/disfavoritism r = .81). We therefore used only the 49 questionnaire items describing the participant's perception of his or her relationship with the chosen sibling. The warmth scale consisted of items describing similarity (e.g., “To what extent do you and your sibling think alike?”; 4 items), intimacy (e.g., “To what extent do you talk to your sibling about things that are important to you?”; 3 items), affection (e.g., “To what extent do you consider your sibling a good friend?”; 3 items), admiration (e.g., “How much do you admire your sibling?”; 3 items), acceptance (e.g., “To what extent do you accept your sibling's personality”?; 3 items), and knowledge (e.g., “How much do you know about your sibling?”; 3 items). The conflict scale consisted of items focusing on quarreling (e.g., “How much do you and your sibling argue with each other?”; 3 items), antagonism (e.g., “How often do you do things to make your sibling mad?”; 3 items), competition (e.g., “To what extent do you feel jealous of your sibling?”; 3 items), and dominance (e.g., “To what extent does your sibling act in superior ways towards you?”; 3 items). In all these subscales, high scores reflected high levels of warmth or conflict in the participants’ perception of their relationship with the chosen sibling. Parental favoritism scales consisted of items concerning maternal and paternal favoritism or disfavoritism of one sibling (e.g., “Do you think your father/mother favors either yourself or your sibling?”; “Do you think your mother is closer to you or to your sibling?”; “Do you think your father/mother supports you or your sibling more?”; 12 items). High scores in this variable reflect parents preferring the respondent, whereas low scores mean that the parent favors the target sibling over the respondent.

The original questionnaire factor scores show high levels of internal consistency and test–retest reliability and low correlations with measures of socially desirable responses (Stocker, Lanthier, & Furman, 1997).

To further investigate predictors of conflict between siblings, we calculated the reliability of the similarity subscale of the warmth scale separately (Items 1, 27, 54, 81: “How much do you and your sibling have in common?”; “To what extent do you and your sibling have similar personalities?”; “To what extent do you and your sibling think alike?”; “How similar are your and your sibling's lifestyles?”). Unlike other subscales, the items of this subscale do not reflect feelings toward the sibling but indicate instead perceptions and cognitions of similarity or dissimilarity.

In the present study, internal reliabilities were Warmth, α = .94; Conflict, α = .88; Parental favoritism, α = .82; and Similarity, α = .82.

Narcissistic Personality Inventory

The Narcissistic Personality Inventory (NPI) is a self-report inventory developed by Raskin and Hall (1979) for the purpose of measuring individual differences in narcissism as a personality trait. It shows high reliability (α = .86, and α = .87; Emmons, 1984, 1987), and has been validated by several studies with clinical and nonclinical populations (e.g., Emmons, 1984, 1987; Rhodewalt & Morf, 1995). Emmons (1984, 1987) discovered four factors in the NPI: exploitativeness/entitlement, leadership/authority, superiority/arrogance, and self-absorption/self-admiration. The NPI uses a forced-choice format with a narcissistic response and a nonnarcissistic response for each item. It consists of 40 statement pairs from which subjects are asked to choose the more accurate self-characterizing statements. The scale yields an overall narcissism score, which is the number of narcissistic statements that the participant endorses and the measure scores for four components of narcissism. In this study, the overall score was used; the higher was the score, the more narcissistic traits were reported. Internal consistency was α = .80.

Results

In keeping with the study objectives, to examine the relations between perceptions of parental favoritism, narcissism, similarity with the sibling, and gender on siblings’ warmth and conflict in emerging adulthood, this section will present the results obtained regarding (a) correlations between narcissism and parental favoritism or disfavoritism and between narcissism and the dependent variables (warmth and conflict in sibling relations); and (b) the contribution of the independent variables (participant and sibling gender, age difference between siblings, parental favoritism, and narcissism) to warmth and conflict in sibling relations, as investigated by means of hierarchical regressions. The regression for predicting conflict between siblings also included perception of similarity between siblings. Since our model assumed that unequal maternal or paternal treatment could moderate the link between narcissism and sibling relations, interaction between these variables was examined in the regression analyses following the standard procedure of Baron and Kenny (1986). Finally, gender differences in sibling warmth, conflict, perception of parental favoritism or disfavoritism, and narcissism and similarity were examined.

Bivariate Associations

Table 1 shows Pearson correlations revealing a positive correlation between maternal and paternal favoritism and warmth and a negative correlation with conflict. These results indicated that perception of parental favoring for the target sibling (contrary to favoring for the respondent) was linked to higher levels of conflict and lower levels of warmth between siblings. A lower but still significant negative correlation was found between narcissism and warmth between siblings, narcissism and maternal favoring for the sibling over the respondent, and between narcissism and similarity; a positive correlation was found between narcissism and conflict.

TABLE 1 Bivariate Associations

	Sibling	>Sibling	Sibling	Maternal	Paternal	Narcissism	Age	Sibling age
Variable	warmth (1)	conflict (2)	similarity (3)	favoritism (4)	favoritism (5)	(6)	(7)	differences (8)
(1)		−.06	.57***	.23**	.26**	−.16*	15*	.04
(2)			−.08	−.21**	−.22**	.15*	.12	.16*
(3)				−.19**	−.20**	−.14*	.07	.06
(4)					.43***	−.16*	−.12	−.05
(5)						.14	−.11	−.10
(6)							−.03	−.07
M	2.34	3.53	3.04	2.34	2.41	1.66	26.67	1.52
SD	.73	.59	.94	.65	.67	.15	.29	.48

Predictions of Warmth and Conflict

Table 2 represents the regression analysis for predicting warmth between siblings, whereas the prediction accounts for 29% of the variance. The first step in the analysis of warmth shows that participants’ gender contributed significantly, adding 7% to the prediction; according to the β coefficient, women reported higher levels of warmth than men. In the second step, paternal and maternal favoritism was found to make a significant contribution, adding another 7%; according to the β coefficient, being favored by the parents predicted sibling warmth (father's favoritism has a stronger impact). In the third step, low levels of narcissism made a significant contribution and added 8% to the prediction; according to the β coefficient, low levels of narcissism predicted warmth. In the fourth step, the interaction between father's favoritism and narcissism contributed an additional 7% to the prediction of warmth. In order to examine this interaction, subjects were divided into two groups based on their score in comparison to the median of paternal favoritism (a score over the median means participant perceived favor from the father, and a score below the median means participant perceived disfavor from the father). In each group, the correlations between narcissism and warmth were calculated. A higher negative correlation emerged between warmth and narcissistic traits when the participants perceived that the father favored the sibling (r = −.40; p < .05) than when the father was perceived as favoring the respondent (r = .0.5; p > .05). This finding suggests that paternal favoritism exacerbates the link between narcissism and siblings’ warmth, when the father favors the sibling (over the respondent).

TABLE 2 Prediction of Siblings’ Warmth (N = 202)

Predicting variables	B	SE B	Beta	t	ΔR ^2
Step 1					.07**
Age	.01	.01	.07	.93
Gender	−.46	.14	−.25**	−3.17**
Sibling age difference	.06	.10	.04	.60
Sibling gender	−.05	.07	−.04	−.54
Step 2					.07**
Maternal favoritism	.64	.29	.15*	2.13**
Paternal favoritism	.22	.08	.23*	3.26**
Step 3					.08**
Narcissism	−.84	.33	−.20*	−2.87**
Step 4					.07***
Paternal favoritism × Narcissism	.32	.12	.26*	3.54**
Note. Higher scores on favoritism indicate high levels of unequal parental treatment. Gender: 1 = + = male; 2 = − = female.

It is worth mentioning that in this analysis, similarity between siblings was not included, as it was originally part of the warmth factor, and high correlations were found between them (r = .58).

Table 3 represents the regression analysis for predicting conflict between siblings, and the prediction accounts for 22% of the variance. It can be seen that in the first step of the regression, sibling gender and age difference between subject and sibling made a significant contribution, adding 11% to the prediction; according to the β coefficient, levels of conflict were higher with sisters than with brothers and higher with a younger sibling than with an older sibling. In the second step, parental favoritism added 1%; according to the β coefficient when the target sibling was perceived as favored (over the respondent) by both mother and father, the conflict with the sibling was higher. Narcissism made a significant contribution and added 3% to the prediction in the third step; according to the β coefficient, high levels of narcissism predicted conflict. In this regression, the fourth step similarity between siblings made no contribution. In addition, the nonlinear component of similarity was introduced in this step to examine the possibility that various levels of similarity contribute differently to sibling conflict. The nonlinear component of similarity contributed significantly, adding 2% to the prediction of conflict; in other words, extreme similarity or dissimilarity contributed to conflict between siblings. In the fifth step, the interaction of gender by age contributed significantly and added 4% to the prediction of conflict. An examination of this interaction revealed that among men, the older they were, the less likely they were to be engaged in conflictual relations with their sibling (r = −.22; p < .05); whereas among women, the older the participant was, the more likely she was to be in conflict with her sibling (r = .20; p < .05). This finding implies that being older predicts conflict between siblings among women but not among men.

TABLE 3 Prediction of Siblings’ Conflict (N = 202)

Predicting variables	B	SE B	Beta	t	ΔR ^2
Step 1					.11**
Age	.02	.01	.15	1.94*
Gender	−.09	.10	−.10	−.98
Sibling age difference	.26	.09	−.22	.60
Sibling gender	−.23	.09	−.20	−2.86**
Step 2					.02*
Maternal favoritism	−.14	.08	−.16*	−2.18*
Paternal favoritism	−.22	.08	−.17*	−2.22*
Step 3					.03*
Narcissism	.19	.09	.17*	2.37**
Step 4					.02*
Similarity	−.02	.00	−.12	−1.81
Similarity ^a	.22	.10	.18*	2.42**
Step 5
Gender × Age	.10	.04	.22*	2.55**	.04**
Note. Higher scores on favoritism indicate high levels of unequal parental treatment. Gender: 1 = + = male; 2 = − = female.

Gender Differences

To examine gender differences in the dependent variables (warmth and conflict between siblings), as well as in maternal and paternal favoritism, narcissism, and similarity, we conducted a multivariate analyses of variance (MANOVA) according to Wilks’ criterion, which revealed significant differences (F(6, 182) = 3.13; p < .01; η² = .09). Univariate ANOVAs (see Table 4) revealed significant differences between men and women in warmth (F(1, 187) = 16.20; p < .001; η² = .08) and similarity (F(1, 187) = 4.83; p < .05; η² = .03): Women reported more warmth and perceived greater similarity in their relations with their sibling than did men. A 2 × 2 MANOVA (Participant's gender × Chosen sibling's gender) was conducted to detect differences in gender dyads (whether male or female participants preferred a brother or a sister as the target sibling in this study); results showed no significant difference (F(6, 177) = 1.61; p = .15), and no significant interaction was found between participant's gender and the chosen sibling's gender (F(6, 177) = 1.40; p = .22).

TABLE 4 Gender Differences

	Women		Men		Group
	(n = 114)		(n = 74)		differences
Dimension	M	SD	M	SD	F(6, 182)	η^2
Warmth	2.80	.74	2.24	.69	16.20***	.09
Conflict	3.65	.56	3.50	.61	Ns
Maternal favoritism	2.18	.65	2.20	.58	ns
Paternal favoritism	2.29	.64	2.29	.62	ns
Narcissism	1.64	.16	1.65	.15	ns
Similarity	3.39	.96	2.98	.94	3.13**	.05

Discussion

The purpose of this study was to evaluate the factors contributing to warmth and conflict in relationships between young adult siblings. We believe that one of the roots of warmth and conflict in adult sibling relations can be traced to the developmental effects of the perception of having been treated differently by the parents in comparison with a sibling. Such perceptions affect one's evaluation of oneself as worthy or unworthy of parental attention and may also affect one's level of narcissism. We further assume that unequal parental treatment moderates the link between narcissism and sibling relationships in young adulthood.

Our results indicated that parental disfavoring (mostly paternal disfavoring) of the respondent affected sibling warmth negatively and that both maternal and paternal disfavoring predicted conflict. In addition, an interaction revealed that paternal unequal treatment moderates the link between narcissism and perceptions of sibling warmth: Being disfavored by the father exacerbates the narcissism, and thus the warmth between the siblings declines. In addition, narcissism contributed to low levels of warmth and to high levels of conflict. A less substantial, yet significant contribution to the prediction of conflict between siblings was extreme levels of similarity or dissimilarity.

Being a woman contributes substantially to sibling warmth, whereas the gender of the sibling and the age difference make a major contribution to conflict between siblings. Thus we found higher levels of conflict between sisters and between younger siblings. Age was also an important factor: An interaction showed that the older women within the cohort reported more conflict, whereas the opposite was found for men. These findings are addressed in greater detail below.

Parental Favoritism, Narcissism, and Sibling Relationships

As previously mentioned, perception of parental favoring for the participant (as opposed to favoring the target sibling) was linked to higher levels of warmth between siblings and lower levels of conflict. These findings concur with other studies reporting that parental attitudes toward the children in the family appear to influence how each sibling perceives himself or herself and the other children in the family (Sheehan & Noller, 2002) and that parental preference of one child over another can compound the hostility and jealousy toward one's siblings in young adulthood (Brody et al., 1998; Garcia et al., 2000; Rauer & Volling, 2007). Our results distinguish between perceptions of being favored versus being disfavored by the parents and emphasize their impact, although Boll, Ferring, and Filipp (2003) claim that the relationship with a sibling was best when both were treated equally and that the relationship diminished with increasing favoritism or disfavoritism.

The results regarding the link between narcissism, differential treatment by parents, and sibling relationships converge with previous theoretical conceptualizations and with studies suggesting that parental devaluation, rejection, or abandonment contribute to narcissistic vulnerability (Emmons, 1987; Kernberg, 1976, 1980; Otway & Vignoles, 2006). As expected, low levels of narcissism contribute to a greater degree of sibling warmth, whereas higher levels of narcissism are associated with greater sibling conflict. Gilbert and Gerlsma (1999), who studied adults (between the ages of 20 and 88 years), reported that recalling having been less favored than a sibling and thus shamed shapes narcissistic vulnerability and shows strong associations with indicators of psychopathology.

According to our results, we may suggest that it would be unlikely that those who are high in narcissistic traits feel close to their siblings and that given the nature of their sensitivity to rejection and especially to parental attitudes that evoke hostility (Bishop & Lane, 2002; Exline et al., 2004), such persons would be involved in conflictual relations with their siblings.

This study considers parental favoritism as a potentially moderating variable for the effect of narcissism on sibling relationships in young adulthood. The interaction of Paternal favoritism × Narcissism suggests that paternal favoritism may increase narcissistic traits and intensify detachment between siblings. These findings raise the question of why paternal disfavoring and not maternal disfavoring was linked to narcissism and sibling warmth. McHale et al. (2000) give some support to our findings; they reported that lower levels of fathers’ involvement, warmth, and disfavoring of their adolescents participants were associated with lower levels of self-esteem. In this vein, it worth mentioning Brody, Stoneman, and McCoy (1992, 1994), whose studies reported that the effects of the father's differential parenting accounted for unique effects in sibling relationships more often than the mother's differential parenting and that the father's unequal treatment was associated with negative sibling relationships. However, due to a paucity of empirical studies, our findings regarding paternal favoritism, narcissism, and sibling relations warrant additional research.

Similarity Between Siblings and Their Relationships

An interesting result was obtained with regard to similarity and conflict between siblings, whereby either very high or very low levels of similarity contributed to conflict. It seems that when they are very much alike, or very different from each other, conflict arises between siblings. One explanation for this finding may be that the two individuals wish to be separate from one another and that extreme similarity might threaten such differentiation (Feinberg, Reiss, Neiderhiser, & Hetherington, 2005; Vivona, 2007); alternatively, extreme dissimilarity provokes conflict. In childhood, siblings form their identity through identification and differentiation (Weaver, Coleman, & Ganong, 2003) and through perceiving and formalizing sameness and differences (Schulman, 1999). Deidentifying fosters the development of a separate and unique personality apart from the sibling and mitigates competition by limiting comparison. Counter identification with siblings clearly delineates the limits of self and defines the other as unlike the self (Charles, 1999; Vivona, 2007). In young adulthood, individuation and the uniqueness of each sibling become more crucial, and similarity to the sibling is used as a means for comparison as well as competition (Boll et al., 2003). Thus, conflict may foster individuation through the recognition of divergence of interests (Ross, Siddiqui, Ram, & Ward, 2004) and may serve as a means for creating room for each individual to foster his or her different and unique identities and to select his or her unique niche (Feinberg et al., 2005).

It is worth mentioning that perceived similarity between siblings was negatively correlated with narcissism, probably because one characteristic of narcissism is the wish to be special, unique, and different from others (Raskin, Novacek, & Hogan, 1991), in our case, from the sibling.

In the literature, very little evidence has been reported of a link between close relationships and the resemblance of personality traits in general and among siblings in particular. Our data extends this literature by examining the contribution of levels of similarity in sibling relationships.

Gender and Age Differences Between Siblings Affecting Sibling Relationships

As already discussed, being a female participant predicted warmth to the sibling, whereas conflict was predicted when a sister was the targeted sibling. We also observed that the older women within a cohort reported more conflict. These results are consistent with previous reports of women being in greater contact with and more likely to give help to their siblings than men (Riggio, 2000, 2006; Spitze & Trent, 2006). We assume that while women are closer to their sisters and brothers, their greater level of emotional involvement may include an increased risk of conflict as well. Our findings are in some ways quite different from those found in other studies. Some researchers have reported that siblings of the same gender are closer than siblings of different genders (Connidis & Campbell, 1995; Lee, Mancini, & Maxwell, 1990; Weaver et al., 2003; White & Riedmann, 1992), whereas Stocker, Lanthier, and Furman (1997) reported that siblings of different genders reported less conflict in their relationships than siblings of the same gender.

Similar to findings reported by Stewart, Verbrugge, and Beilfuss (1998) and those of Riggio (2006), our data showed that participants displayed higher levels of conflict if the targeted sibling was younger than were they. Adler (1968) theorized about the unique psychological situation of each birth position within families, with the firstborn as dominant and having a great deal of power; the younger of two siblings as constantly competing and resistant to control by the firstborn; and the youngest child in larger families as the “baby” who is pampered and spoiled. Freud (1916–1917) referred to competition for parental resources and claimed that the younger sibling erodes the emotional position of the older child in the family. The younger sibling is viewed as an obstacle to the parents’ attention and a rival with whom he or she must share the parents’ love; consequently, the younger sibling's very existence evokes power struggles, jealousy, anger, and aggressive fantasies (Angel, 2006). We suggest that in adulthood, siblings continue to be sensitive to discrepancies in their parents’ behavior and that sharing parental resources of love and attention may evoke conflict, especially if the sibling is younger.

Limitations

Our study has several limitations, the first of which is that it reflects a snapshot of sibling relations at one point in young adulthood, and is not, therefore, a longitudinal examination. Thus, it is difficult to ascertain whether the narcissistic traits we identified stemmed from parental differential treatment or whether this personality construct manufactured the perception that the parent preferred the sibling. Our results warrant further examination and may be best evaluated in longitudinal studies that begin with child or adolescent subjects who are then followed well into adulthood. Another limitation in this study arose from the fact that only participants portrayed their relationships with their siblings, whereas the point of view of the siblings may have enriched our understanding of the relations and enabled us to study both individuals’ perceptions of the relationship. Furthermore, our participants were asked to choose one of their siblings as their reference, a procedure which could have resulted in biased characterizations of the sibling relationship if the selected sibling tended to be the one with whom they had the most congenial or the most conflictual relationship.

Our sample was predominantly middle- to upper-middle class, and was composed of undergraduate and graduate students. Research using persons of more varied educational and socioeconomic status is needed to determine the universality of the present findings. In addition, two thirds of our participants were women, since most were recruited from the Social Sciences and Humanities faculties where, in Israeli universities, women are the majority. In further studies, the sample should be more gender balanced. Finally, our findings—which indicate associations between parental favoritism and both (a) narcissism and (b) sibling relations—suggest the need for further research examining other personality variables such as envy and differentiation of the self, which may enrich our understanding of sibling relations.

Conclusion

The main contribution of our study has been to link parental favoritism to adult sibling relations. This study examined the moderating effect of parental favoritism or disfavoritism on narcissism, affecting sibling relationships in young adulthood. Narcissism, as a personality variable, is a good indicator of relationship quality because the presence of narcissistic features powerfully affects relationships and often predicts conflicted interpersonal relationships. Narcissistically driven individuals are particularly sensitive to how their parents treat them, and their perceptions of unequal parental regard may moderate or exacerbate conflict and warmth in sibling relations. We believe that although the role of narcissism in sibling relations has not been documented thoroughly yet, it is worthy of additional attention, given that our study has found that high levels of narcissism hinder warmth and contribute to conflict in sibling relationships. However, our assumptions were not fully confirmed; findings showed only that paternal unequal treatment moderates the link between narcissism and perception of sibling warmth.

Clearly, relationship dynamics are affected by a multitude of intervening variables, and we expect that future research will conclude that narcissism plays a significant role, especially when a narcissistically driven personality is confronted by unequal parental treatment.

AUTHOR NOTES

Ricky Finzi-Dottan is a senior lecturer and faculty member at Bar Ilan University's School of Social Work. Her current research interests are family relations, motherhood, fatherhood, and child abuse. Orna Cohen is a senior lecturer and faculty member at Tel Aviv University's School of Social Work. Her current research interests are family relations, fatherhood, and divorce.

Notes

*p < .05.

**p < .01.

***p < .001.

*p < .05.

**p < .01.

***p < .001.

^aThe nonlinear component of Similarity.

*p < .05.

**p < .01.

**p < .01.

***p < .001.