Chunk #61 — II. G × E Interaction in Aggressive Behavior — A. Potential moderators of genetic influence found in adoption and twin studies — 1. Family adversity and social disadvantage
There are also a few studies based on twin samples that have used the moderated variance components approach to examine whether measured environmental (risk) factors moderate the genetic and environmental variances for aggressive behavior. For example, the heritability of conduct problems was found to be lower in children growing up in dysfunctional families and higher in children growing up in families where dysfunction was absent (Button et al., 2005). Another twin study used DeFries-Fulker regression analysis to examine whether genetic and environmental influences on aggressive behavior varied depending on levels of family warmth (DeFries and Fulker, 1985). Genetic influence on aggressive behavior was found to be higher in schools with higher average levels of family warmth. In contrast, environmental influences (both shared and nonshared) were more important in schools with lower average levels of family warmth (Rowe et al., 1999). These findings suggest that genetic effects are more likely to explain individual differences in aggression in more benign environments, whereas in more disadvantaged environments negative family-related factors and context-dependent risks may play a greater role than genetic predispositions in aggressive and antisocial outcomes.
