ABSTRACT
The tendency for schizophrenia to run in families has long been recognized. A century ago, Emil Kraepelin, who described the syndrome of `dementia praecox', the forerunner of schizophrenia, noted: `I had myself found formerly in Heidelberg general hereditary predisposition to dementia praecox in about 70 per cent of the cases in which about this point reliable statements were to hand' (Kraepelin, 1919). Since Kraepelin's initial observations, overwhelming evidence has emerged from family, twin and adoption studies that schizophrenia has a strong genetic component.
