This secondary data analysis was based on data obtained from the adolescent/young adult female twin participants and their parents as part of the Missouri Adolescent Female Twin Study (MOAFTS; NIAAA AA09022, PI Heath). The study targeted all twin pairs live-born in Missouri between 1975 and 1987. Of those families identified, an 87% participation rate was achieved for the initial interview, thus providing a large representative sample of the population of female twins in Missouri (Heath et al., 1999). Baseline assessments included an initial parental interview and an expanded diagnostic interview obtained from the parents of 2,369 families and from each adolescent twin girl between the ages of 13 to 19 years (N = 3,582) together with an adolescent questionnaire (N = 2,080). There were 434 Black adolescent girls in this sample; other adolescents were almost entirely of European ancestry. Five years later, all originally targeted adolescent, now young adult, women were again contacted. For those completing wave 1, the participation rate was 84% at wave 2, and some earlier nonparticipants were added. Median age at baseline and follow-up was 15.8
