Capitalizing on coordinated ascertainment and assessment protocols, we combined samples of offspring of maternal and paternal alcoholics and their co-twins. As a result, we are unable to examine separately the effects of maternal versus paternal alcoholism on offspring outcome within the COT design, owing largely to reduced statistical power from analyzing each sample separately. This is especially true for internalizing, where combined samples lack statistical power necessary to distinguish among genetic and environmental risks. In addition, we used mother report of offspring behavior problems if valid CBCL data were available from both a biological mother and twin father. Although reports from both parents were available from only a handful of families, using a structural equation modeling rather than regression-based framework for data-analysis would enable incorporation of data from both parents, while allowing for potential rater biases associated with parental psychopathology.
