Using an offspring of twins design identical to the present study design we have modeled the family and non-family environmental contributions to cannabis abuse/dependence while accounting for the heritability of this disorder (Scherrer et al. 2008). The present study utilizes the offspring of twins design to: 1) test for bivariate associations between parent, sibling and peer level variables and offspring smoking initiation, regular smoking and ND and 2) determine which family and non-family environmental contributions to smoking initiation, regular smoking and ND remain significant after controlling for familial vulnerability. We hypothesize that parent, sibling and peer influences will be significant predictors of offspring smoking outcomes even after adjusting for variance due to familial factors.
