Among EA twins, those from separated alcoholic families were at highest risk compared to twins from intact nonalcoholic families. Effects were most pronounced during early and middle adolescence, where age-interactions were necessary to correct for PH violations. In unadjusted models, EA twins from separated alcoholic families were at 6.17 times increased likelihood of sexual onset through age 14, and over 2 times increased likelihood over ages 15–17. Risk associated with intact alcoholic families and separated nonalcoholic families were also elevated. EA twins from intact alcoholic families were at over 3 times increased likelihood of sexual onset through age 14, and 1.53 times increased likelihood over ages 15–17. Parental separation in the absence of parental alcoholism was associated with over 3 times increased likelihood of sexual onset through age 14, and 1.81 times increased likelihood over ages 15–17. Reduced effects of parental separation and parental alcoholism were observed in covariate-adjusted models, with risk to EA twins through age 14 significant across risk-group.
