These findings add to the growing literature underscoring the importance of studying how environmental factors interact with genetic predispositions to understand pathways of risk that contribute to deleterious outcomes, rather than simply testing for main effects of genes and environments. Interestingly, we find no interactive effects of neighborhood influences and genetic susceptibility with respect to alcohol use at age 14. At age 14, the majority of individuals in our sample (64%) had not yet initiated alcohol use. Of those who had reported initiation, 21% reported using alcohol “rarely,” another approximately 13% reported drinking 1 to 2 times monthly, and approximately 3% weekly (Rose et al., 2001b). At this early stage of the initiation and establishment of alcohol use, we find only modest evidence of genetic influences (approximately 27%), in line with other studies finding that the initial stage of alcohol use are largely influenced by common environmental factors (Hopfer et al., 2003). We know that dramatic changes occur in the relative importance of genetic and environmental influences on alcohol use across adolescence, as individuals move from initial experimentation to more
