Callous-Unemotional Traits Moderate Genetic and Environmental Influences on Rule-Breaking and Aggression: Evidence for Gene × Trait Interaction

Previous behavioral genetic research in children has found that conduct problems in the presence of high CU traits are more heritable than conduct problems in the presence of low CU traits—a gene × trait interaction. The current study replicates and extends this finding using a sample of adolescent twins from the Texas Twin Project, who were assessed for rule-breaking and aggression. We find evidence that genetic influences on CU traits contribute to genetic liability for both rule-breaking and aggressive behavior. CU traits moderate genetic influences on aggressive behavior, such that the heritability of aggression is higher among youth with high levels of CU traits. However, we do not find evidence that CU traits moderate genetic influences on rule-breaking behavior. The continuum of callous-unemotionality and the aggression versus rule-breaking distinction continues to be meaningful and intersecting methods for characterizing heterogeneity in the etiology of antisocial behavior.