Perhaps most importantly, proximal causal mechanisms remain unknown. Behaviors or conditions genetically correlated with AUD and not parental AUD per se, may explain the association between parental alcoholism and externalizing and total problem behaviors. Likely candidates include comorbid parental psychopathology, such as antisociality and depressive disorders, both of which show moderate to high genetic variation, and are strongly correlated with AUD (Fu, Heath, Bucholz, Nelson, Goldber et al., 2002; Prescott, Aggen, & Kendler, 2000; Slutske, Heath, Dinwiddie, Madden, Bucholz et al., 1998; Slutske, Heath, Madden, Bucholz, Statham, & Martin, 2002). A related limitation concerns transmission of risks associated with co-parent AUD, which was unmeasured in the present analysis. To the extent that co-parent AUD, including co-parent comorbid psychopathology, are not included in COT models, this model-misspecification may lead to false inference (see Eaves, Sliberg, & Maes, 2005).
