The Missouri Adolescent Female Twin Study (MOAFTS)30,31 is a population-based longitudinal study of female twin pairs born between July 1, 1975 and June 30, 1985 in Missouri to Missouri-resident parents. The sample was demographically representative of the Missouri population at the time the twins were born, with nearly 15% of twins being Black and the remainder being of White descent. A baseline interview was conducted with 3,258 twins beginning in 1995 (median age = 15 years). Between 2002 and 2005, all twins from the target cohort (excluding those who had withdrawn from the study or whose parents asked that the family not be recontacted) were contacted for Wave 4 interviews (N = 3,787). Wave 5 interviews were conducted between 2005 and 2008 with 91% of the Wave 4 participants.
