In summary, the present study extends previous findings indicating that two components of genetic risk related to problematic alcohol use change across development. Results indicated that alcohol-specific genetic risk factors increase in importance across adolescence and are most important during early adulthood (age 22); in contrast, non-specific genetic influences related to externalizing behavior decrease in importance across this same developmental period and are most important during early adolescence (age 14). In an important extension of previous work on this topic, we found that the relationship between genetic risk and problematic drinking across development is moderated by the individual’s sex and his/her co-twin’s sex. AUD-GR influenced alcohol outcomes in females earlier in adolescence than in males and by age 22, AD criteria are influenced more by EXT-GR for males than females. In addition, the association between genetic risk and intoxication frequency was greater among 14 and 17 year old females with male co-twins. Together, these findings highlight the importance of assuming a developmental perspective on the role of genetic influences on alcohol use behaviors during adolescence and young adulthood.
