Because rates of problematic drinking behavior are typically greater in males, we examined whether sex differences moderated the relationship between AUD-GR, EXTGR, and alcohol outcomes across development. Overall, the relative influence of AUDGR and EXT-GR on alcohol use behaviors across development was maintained; in early adolescence, genetic influences on alcohol use and problems are largely non-specific and later in adolescence and young adulthood, alcohol specific genetic influences on alcohol use are more influential. However, within each of these trajectories, several interesting sex differences emerged. Most striking is the relatively early influence of AUD-GR on alcohol use behaviors in females. Twin studies have indicated that genetic influences on drinking frequency emerge in girls at a younger age than boys (Maes et al. 1999; Rose et al. 2001), which may be a result of increased early alcohol use, pubertal timing, and having a greater number of older friends who may provide access to drinking opportunities. Earlier access to alcohol and earlier evidence of heritability in drinking frequency may also be related to the earlier influence of alcohol specific risk for intoxication frequency
