Schizophrenia in Twins: 16 Years' Consecutive Admissions to a Psychiatric Clinic

Recent developments in the vexed questions of the relative importance to be attributed to genetic and environmental factors in the aetiology of schizophrenia, and the manner in which they interact to produce a phenotypic psychosis, are highlighted by David Rosenthal's series of critical papers (1959–1962) on twin and family studies and the book edited by him chronicling the lives of a set of monozygotic quadruplets all concordant for schizophrenia (1963). In his thorough and open-minded critique Rosenthal argues that previously reported concordance rates for monozygotic (MZ) twins have been misleadingly high. To this point we shall return in a moment. Rosenthal finally concludes that “the best information we now have with respect to the whole broad question of heredity and environment in schizophrenia, is to be found mainly in the five major studies of twins.” Unlike some who have pointed out weaknesses in the studies, he believes that “our task is to determine their source, extent and implications, not to dismiss them offhandedly because they contain errors” (1962a, p. 132).