Criminologists have long noted that offenders are more likely to be the victims of crime as compared to nonoffenders. What has not been established, however, is why there is a significant degree of victim-offender overlap. While numerous explanations have been advanced and a significant number of studies have been conducted, there remains much to be learned about the etiology of the victim-offender overlap. The current study pushes this line of research forward by offering and testing a unique hypothesis: that victimization and offending share a genetic etiology that leads to victim-offender overlap. Findings culled from a sample of sibling pairs drawn from the National Longitudinal Study of Adolescent Health indicated that genetic factors explained between 51% and 98% of the covariance between victims and offenders. Nonshared environmental factors explained the remaining covariance, while shared environmental factors explained none of the covariance. Implications and interpretations of these findings are considered.