Survival analyses are based on parent interviews and Waves 1, 3, 4 and 5 twin interviews. Twins were selected if they had data on lifetime substance (alcohol, tobacco or illicit drug) use and both parental alcoholism and parental separation, resulting in a sample of 4163 individual twins (613 AA, 3550 EA) from 2139 families (320 AA, 1819 EA). At last completed assessment, twins ranged in age from 12 years (Wave 1) to 31 (Wave 5), with AA twins approximately one year older on average [AA M(SD)=17.91(3.79)] than EA twins [M(SD)=16.71(3.30), t1=8.10, p=0.0001]. Additional sample characteristics are provided in Supplementary Table S11, separately by race/ethnicity and presence versus absence of parental alcoholism and parental separation.
