because they are specific measures of environmental exposure to alcohol use, whereas the scale of deviant peer behavior that we used reflected the proportion of peers engaging in a wider variety of externalizing behaviors. Because this ALDH2 polymorphism influences alcohol use via a known mechanism which specifically affects alcohol metabolism, ALDH2 would not be expected to contribute to variation in the largely genetic latent factor which likely influences alcohol use and other externalizing behaviors in common (Krueger et al., 2002). Peer deviance in general, although highly correlated with adolescent alcohol use (Sher et al., 2005), may be too indirectly related to environmental alcohol exposure to moderate the influence of ALDH2 genotype. SIBS study participants were residents of Minnesota, where alcohol use and binge drinking in adolescents and young adults are substantially above mean national levels (Substance Abuse and Mental Health Services Administration, 2010), so the omission of a sensitive and specific measure of peer alcohol use may be critical.
