Abstract
Family genetic data, based on standardized and independent diagnostic procedures of index and secondary cases, confirmed the dichotomy between schizophrenias and affective disorders. The classical schizophrenic subtypes exhibited a significant tendency towards homotypia among their secondary cases. The genetic evidence did not support the monopolar-bipolar subdivision of affective disorder. Schizo-affective disorders impinged on the clear-cut schizophrenic and affective psychotic disorders and there was no homotypical tendency among the relatives of index cases with this diagnosis