This is the first study to examine the genetic relationship between peer alcohol use and adolescent alcohol use. The study replicated previous findings of a strong association between peer and adolescent alcohol use [5–7]. The results indicated a high level of overlap between the genetic influences on both friends' drinking and adolescent alcohol use, as indicated by the significant genetic correlations (r = 0.6–0.7). However, the results also emphasize the importance of environmental factors with the majority of the common environmental factors being shared.
