parental separation in cases where it followed the onset of the substance use outcome. Findings indicated that parental separation prior to age 18 was associated with earlier onset of drinking and alcohol intoxication (Waldron et al., 2014a; 2014b), even controlling for family background characteristics and history of psychopathology and abuse (although in the sample that included African Americans, the association was found only in European Americans). Grant et al. (2015) applied the same approach to the examination of three stages of alcohol use in a combined sample drawn from two offspring of twin studies and also found an association between parental separation and elevated risk for early alcohol use initiation. However, in all of these studies that drew from twin and offspring-of twin samples, data were collected retrospectively. The influence of parental divorce on drinking initiation has not been examined prospectively, which minimizes bias in the recall of age of first drink.
