The second aim of this study was to explore environmental moderation of genetic effects on alcohol consumption. These analyses yielded three particularly noteworthy results. First, environmental moderation of genetic effects was much more pronounced in early and mid-adolescence than in later periods. Genetic effects on alcohol use seem to be much more environmentally sensitive at this early developmental stage. As use patterns become more established, genetic effects may become less flexible and open to environmental moderation. These results have obvious implications for prevention efforts. Environmental interventions that occur in adolescence might be capable of substantially attenuating the effect of high genetic risk. Similar interventions in early to mid-adulthood may be much less efficacious as the system has become more developmentally canalized.
