The present sample consists of adolescent twins who participated in wave 2 of the G1219 study—a longitudinal study of twins and their families. Full details of the study are given elsewhere (McAdams et al. 2013). At the first wave of the study participants were 3,640 adolescents aged 12–19. At the second wave 2,647 individuals took part (73 % of the original sample). Wave 2 questionnaires were completed an average of 8 months (range = 0.8–22 months) after initial contact. Wave 2 was used for the present analyses as it is the wave containing the most environmental measures.
