traits may also play a role in alcohol vulnerability transmitted within families. These traits are visible and measureable at an early age, are highly heritable (Krueger et al., 2002; Price et al., 2001; Slutske et al., 1997), and have previously been postulated as important in the development of alcoholism (e.g. Sher et al., 1999). Our finding of a small effect was in line with the results of longitudinal studies of child behavior from non-referred samples (e.g. Caspi et al., 1995) and similar to predictions of child behavior by parental alcoholism (Martel et al., 2009). Our reliance on maternal report of alcohol problems for both sides of the family may have decreased precision of measurement. Also, our cross-sectional data did not permit us to untangle the temporal order of BD and CP, but recent prospective longitudinal studies have found support for developmental progression models in which traits akin to those in our “BD” construct (e.g., “reactive control” in Martel et al., 2009 or “hyperactivity” in Tarter et al., 2007) lead to later alcohol or substance use outcomes via the subsequent development of additional externalizing behavior problems.
