Logistic regression results along with associated ORs and confidence intervals for the lifetime prevalence of tobacco, alcohol, and marijuana use are given in Table 2. Across all adolescents, adoption status was unrelated to ever using any of these substances. Exposure to parent smoking was, however, associated with ever having used each of these substances. Within the adoptee subsample, those exposed to parent smoking were slightly but significantly more likely to use tobacco (OR=1.68) and marijuana (OR=1.95). Within the non-adopted subsample, those exposed to parent smoking were significantly more likely to use not only tobacco (OR=4.17) and marijuana (OR=3.43), but also alcohol (OR=5.08). Thus, exposure to parent smoking placed adolescents at risk for tobacco and marijuana use, whether the rearing parent was biologically related or adoptive. When the parent was biologically related, the adolescent was at risk for tobacco, marijuana, and alcohol use. The interaction between adoption status and exposure was significant for tobacco and alcohol use, indicating a larger exposure effect in biologically related families.
