The environmental effect of exposure to parent smoking, demonstrated in adoptive families, is consistent with studies showing a reduced risk for tobacco use in offspring of parents who have stopped smoking when compared to adolescents whose parents are current smokers26. Interestingly, adopted adolescents exposed to parent smoking were also at increased risk for marijuana use as well as alcohol use, although the latter did not reach conventional levels of statistical significance. This suggests that the environmental mechanism at play may not be behavioral modeling or access per se, but rather increased parent tolerance for offspring substance use or reduced authority in regulating offspring substance use when the parent is a regular smoker. Alternatively, it may reflect the role of smoking as a gateway to the use of other substances27.
