Genetic Contributions to Adolescents' Extrafamilial Social Interactions: Teachers, Best Friends, and Peers

The purpose of the present study was to investigate genetic and environmental contributions to individual differences in adolescents' social interactions outside the family. We investigated sibling resemblance for adolescents' reports of interactions with best friends and teachers, and parents' perceptions of adolescents' peer groups in 701 same-sex adolescent sibling pairs aged 10-18, using a twin, full sibling, and step sibling design. Our goals were to assess the magnitude of sibling resemblance, and to disentangle resemblance due to shared genetic heritage from that due to shared environmental experiences. Substantial genetic influence was found for parents' perceptions of adolescents' peer groups. Adolescents' reports of positive interactions with teachers and best friends also showed significant genetic influence. In contrast, individual differences in adolescents' reports of negative interactions with teachers and best friends showed no significant genetic influence. In addition, most environmental influences for social interactions with teachers, best friends, and peers were largely of the nonshared variety, suggesting that growing up in the same family does not make adolescents similar in their extrafamilial social interactions.