Strengths of the present study include data from multiple reporters (parents, teachers, and adolescents) across two samples, as well as genotypic information on GABRA2 in order to examine whether parental externalizing behavior exerts an indirect effect on adolescent externalizing behavior via elevations in life events, and whether life events interact with adolescents’ GABRA2 genotype such that this pathway is stronger for some genotypes compared to others. Despite these strengths, the results of the present study should be interpreted in the context of several limitations. First, analyses were limited to Caucasians. Doing so reduces the risk of false positives due to population stratification; however, generalizability to other racial groups is limited as a consequence. Previous work from the Collaborative Study on the Genetics of Alcoholism suggests that self-reports of race/ethnicity are highly correlated with ancestry informative markers (unpublished data), which reduces concerns that population stratification may be driving the significant G × E effects observed in CDP. In FinnTwin12, principal components analyses of the population structure performed in Eigenstrat indicated a single dimension of ancestry. Second, although we are able to
