The cross-sectional nature of this study does not allow psychological, environmental, or genetic effects related to parental alcoholism to be distinguished, and more research is necessary to explain the current findings with respect to these factors. Several additional limitations of these data should be acknowledged. One limitation is that the data do not allow us to examine the relative ages of onset of parental alcoholism and offspring psychopathology. It is also possible that parental alcoholism had a greater effect on advancing the onset of psychiatric illness in offspring, artificially increasing prevalence rates in younger respondents with a parental history. This potential bias would have been reduced, however, by adjusting for age in multivariable models. The reliance on offspring to both diagnose and recall their parents’ alcoholism is another limitation. For example, a reporting bias wherein daughters of alcoholic mothers recall differently than sons of alcoholic mothers could have occurred – leading to the apparent relationship between maternal alcoholism and mania, nicotine dependence, and schizoid personality disorder in female offspring. Such a bias would have likely been present in previous studies
