Reliability of sibling reports on parental drinking behaviors

Questionnaire data from the Colorado Alcohol Research on Twins and Adoptees (CARTA) were analyzed to explore the reliability of sibling responses to items from the CARTA Family Alcoholism History Questionnaire (FHQ) concerning parental drinking behaviors. Subjects included 142 pairs of male and female, twin and nontwin siblings who reported on paternal and maternal problem drinking. FHQ items were summed to produce drinking-problem scales for fathers and mothers. There was generally good concordance across sibling reports of parental problem-drinking symptoms. There was a significant gender difference in that male offspring were more in agreement about their mothers' drinking behavior, while female offspring were more in agreement about their fathers' drinking behavior. For the most part, objective items, such as having two or more drunk-driving arrests, were more reliable (paternal kappa total = .56, maternal = .66) than subjective items, such as being happy only when drinking (paternal = .24, maternal = -.03). This evidence for reliability of sibling reports about parental drinking does seem to validate the use of such questionnaire data in alcohol studies.