Consistent with the findings for smoking and drinking, the model (Model 3a) estimating co-occurrence of risk behaviors, i.e., engaging in both smoking and drinking, revealed that adolescents outside of two biological married parent families were more likely to both smoke and drink. For single-mother families, the odds ratio was about 1.4. Similarly, for married stepfamilies, the odds ratio was 1.5. For adolescents in cohabiting stepfamilies, the odds of engaging in both smoking and drinking were 2.2 times that of the odds for adolescents in two biological married parent families. Indeed, the odds that those who live in a cohabiting stepfamily both smoked and drank significantly exceeded those of all other adolescents.
