Several twin studies examining the role of GxE in alcohol use suggest that genetic influences on alcohol-related behaviors vary under different circumstances (Young-Wolff, Enoch, & Prescott, 2011). Further, these studies emphasize the importance of many different types of environmental risk factors for drug use in general. Twin and family studies testing the role of GxE in alcohol use have focused on the role of distal and proximal environmental exposures. Distal environmental exposures refer to those for which the individual does not directly engage or influence such as neighborhood-level influences and availability of of alcohol. Proximal environmental influences refers to those where the individual has direct engagement and may possibly influence such as peer use and parental monitoring (Dick & Kendler, 2012a). In general, these studies indicate that genetic influences from late adolescent alcohol use are higher in urban environments, communities with greater migration, and communities with higher proportions of older adolescents and young adults.
