As highlighted by Dr. Volavka et al., parsing sources of variation in any putative genetic association is necessary to increase inferential power, especially when etiological heterogeneity is possible, as in schizophrenia. We discussed possible reasons for discrepancies between case-control and family-based studies (e.g., higher functioning of patients in intact trios, greater susceptibility of case-control studies to effects of population stratification [pp. 473–474]). Also, the scientific basis for ethnic differences in association with many phenotypes (including mental illnesses) is by now well established (1). Far from entering the realm of eugenics, we believe that it is essential to capitalize on important genetically mediated differences between subgroups of individuals in order to understand etiological differences between their forms of illness and their variable responses to specific treatments, interventions, or preventive measures.