Enormous industry has been devoted during the last half-century to establishing the genetic contribution to the aetiology of schizophrenia. Demonstration of a familial concentration of the disorder among the blood relatives of schizophrenics is supported by the differential concordance for schizophrenia found between monozygotic and dizygotic twins (Slater and Cowie, 1971; Gottesman and Shields, 1972; Shields, 1978). An alternative explanation offered was that the high familial incidence of schizophrenia was accounted for by the influence of a schizophrenic parent, particularly mother, or a sibling, or by a schizophrenogenic family configuration or pattern of communication. This speculation has been dispelled, however, by the brilliant series of studies which compared the outcome in the offspring of schizophrenics brought up at home with that of those adopted and brought up away from the schizophrenic parent (Heston and Denney, 1968; Ketyet al, 1968; Rosenthal, 1970; Rosenthalet al, 1971; Wenderet al1971; Kety and Matthyse, 1972; Wenderet al, 1974).