reflect enhanced independence associated with the attainment of adult status. Twin data have indicated that environments that exert less social control and/or provide greater opportunity to engage in alcohol use allow for greater expression of genetic predispositions (Dick and Kendler 2012). This has been shown, for example, with respect to low parental monitoring (Dick, Purcell et al. 2006), higher peer deviance (Dick, Pagan et al. 2007; Harden, Hill et al. 2008; Button, Stallings et al. 2009), and communities with higher alcohol sales and less stability (Dick, Rose et al. 2001), all of which are associated with greater genetic variance. Here, we demonstrate that the effect of a specific gene on high risk alcohol use becomes evident during the transition to adulthood. Although we did not directly measure environmental characteristics in this study, this transition is generally associated with the attainment of greater autonomy and fits in the broader theoretical mechanism suggested by the gene environment interaction literature (Shanahan and Hofer 2005; Dick and Kendler 2012).
