The genetic effect size in these complex scenarios is generally very small requiring adequate sample size. We were not able to detect any significant genetic main effect on externalizing behavior and the subscales, rule breaking and aggression. This may be due to the small sample size or the lack of a main effect at the age of 15–17, or most likely, to the strong effect that involvement with delinquent peers has upon these relationships. Finally, replication of these results is needed to further understand the role of GABRA2 on the relation of social context and behavior in adolescents.
