were also observed, particularly for smoking and use of cannabis or other illicit drugs. Twins from nonalcoholic families where parents separated were at nearly three times increased likelihood of smoking before age 11, and nearly two times increased likelihood over ages 11-14. Through age 14, parental separation alone predicted over two times increased likelihood of regular smoking and cannabis use. Twins from nonalcoholic families where parents separated were 3.73 times increased likelihood of other illicit drug use before age 15, and nearly two times increased likelihood from age 15 onwards. Similar but somewhat attenuated effects were observed in covariate-adjusted models.
