To date, a handful of COT studies of alcoholic families have been conducted. For early and problem use of alcohol, evidence of environmental transmission from parental alcoholism has been documented in some but not all reports (Duncan et al., 2006; Jacob et al., 2003; Sartor et al., 2007; Slutske et al., 2008). COT studies based on twin and cotwin history of divorce have been conducted as well, with evidence broadly suggestive of environmental transmission across a range of substance use outcomes (D’Onfrio et al., 2005, 2007). The present study is distinct from earlier work in that we examine timing of alcohol, cigarette and cannabis involvement as a function of parental separation or divorce, employing a COT design to control for genetic and environmental risks from parental substance dependence, including risks from parental cannabis dependence.
