al., 2004), we hypothesized that genes originally associated with adult alcohol dependence would be associated with behavior problems at earlier stages of development. We also hypothesized that the association between the gene and behavior problems would be moderated by environmental factors related to social control and opportunity, per the twin literature on GxE interaction effects. In particular, we tested for a moderating role of parental monitoring and peer antisocial behavior, based on our findings from the Finnish twin studies. We hypothesized that the association between the high-risk genotypes and externalizing behavior would be stronger under conditions of lower parental monitoring and higher peer deviance, based on the twin evidence that the overall genetic influence observed in the population was greater under these conditions.
