Objective: Externalizing and internalizing problems may aggregate in families because (1) siblings share genetic risks for problem behaviors or (2) siblings are exposed to similar environmental risks. A genetically sensitive design was used to determine whether domestic violence accounted significantly for the variation and covariation of externalizing and internalizing problems, independent of additive genetic effects on these behavior problems.
Method: Using the Achenbach family of instruments, mothers and teachers reported internalizing and externalizing problems for 1,116 monozygotic and dizygotic 5-year-old twin pairs in the United Kingdom (93% response rate). Mothers reported their experiences of domestic violence in the previous 5 years. Structural equation models were tested to determine the effect of mothers' experiences of domestic violence on children's emotional and conduct problems, controlling for latent genetic and environmental effects on these behaviors.
Results: A multivariate model showed that adult domestic violence accounted for 2% and 5% of the variation in children's internalizing and externalizing problems, respectively, independent of genetic effects. The co-occurrence of externalizing and internalizing scores was accounted for by genetic (62.6%) and shared environmental (29.2%) factors and by domestic violence (8%).
Conclusions: Because domestic violence affects children's behavior problems beyond genetic influences, programs that successfully reduce domestic violence should also prevent children's psychopathology.