Previous studies have demonstrated that genetic influences on alcohol-related outcomes have both an alcohol-specific component and a general externalizing component of behavior (Kendler et al. 2003; Kendler et al. 2007). The relative importance of these two sets of genetic influences across development has been understudied. Further, differences in these developmental trajectories by sex remain unexamined. Using prospective reports and diagnostic interview data of alcohol use, AD, CD, and ASB from a population based, longitudinal sample of Finnish twins, our results indicate that specific and non-specific genetic influences on alcohol use behaviors have different development trajectories. Specifically, these results suggest a more robust prediction of alcohol outcomes (initiation of use at age 12 and frequency of intoxication at age 14) with genetic risk for externalizing behaviors earlier in adolescence (12-14), and in contrast, a more robust prediction of alcohol outcomes (frequency of intoxication at age 17 and AD symptoms at age 22) with genetic risk specific to alcohol use behaviors in later adolescence into young adulthood (17-22). Importantly, within these overall trajectories, several interesting sex differences emerged, effects that are masked
