Risk Heterogeneity and Recurrent Violent Victimization: The Role of DRD4

Abstract

For some people, victimization comes with significant costs. One of these costs is the likelihood of being victimized a subsequent time. Unfortunately, research shows that a portion of victims do in fact experience more than one victimization. Although this likelihood has been established, the reasons why some people are victimized more than once are not fully understood. One explanation centers on individual risk factors that, if left unchanged, will increase risk of further victimization. Previously unstudied, however, are genetic factors that may place and keep a victim at risk, even after an initial victimization. Using data from the National Longitudinal Study of Adolescent Health, the current study addresses this gap. The findings reveal that there is in fact a genetic factor, the 7R allele of the DRD4 gene, that distinguishes individuals who have been victimized once from those who have been victimized multiple times.

This research uses data from Add Health, a program project designed by J. Richard Udry, Peter S. Bearman, and Kathleen Mullan Harris and funded by Grant P01-HD31921 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, with cooperative funding from 23 other federal agencies and foundations. Special acknowledgment is due Ronald R. Rindfuss and Barbara Entwisle for assistance in the original design. Persons interested in obtaining data files from Add Health should contact Add Health, Carolina Population Center, 123 W. Franklin Street, Chapel Hill, NC 27516-2524 ([email protected]). No direct support was received from grant P01-HD31921 for this analysis.

Notes

¹Other research has found that DRD4 is related to cognitive and behavioral problems in children, but the finding was in the opposite direction (Birkas et al. 2005).

²Only those participants who had full siblings or twins in the sample were asked to participate in the genetic subsample.

³Given the link between involvement in delinquency and victimization, a measure of delinquent involvement was created but not included in the final model as it was significantly and strongly correlated with each exogenous variable, except for race. Inclusion in the model resulted in coefficients changing signs from the original model, which is an indication of multicollinearity (Greene 1997).

⁴Analyses were run for the subsample of female respondents. DRD4 was not significant in either the model predicting victimization or the model predicting recurring victimization.

⁵One of the statistical requirements of the bivariate probit model is that the same explanatory variables cannot be included in the both the selection and outcome equations for the model to be identified (Greene 1997). For this reason, the DRD4 gene was included in the outcome model, and the neighborhood advantage variable was included in the selection model. When included in the nonvictim/victim model, DRD4 is not significant.