The genetic basis for schizophrenia

There is a genetic basis for schizophrenia, and not just for mental abnormality in general, but its existence rests on general considerations and on the occurrence of schizophrenia in relatives of patients in a way that excludes any reasonable alternative explanation. Recent twin and adoption studies have helped to place the role of genetic factors in perspective. No simply inherited enzyme deficiency or other biological defect has been demonstrated in schizophrenia so far, and it may be that inheritance is polygenic, as in most common disorders. If it is agreed that the genes are necessary but not sufficient for the development of schizophrenia, it follows that the environment is also necessary but not sufficient. At present it appears that the environmental contribution is less specific, and that the genes have the privileged status of what has been called the most uniformly potent cause.