Do women without a family history of schizophrenia have a later onset of schizophrenia?

The relation among age at onset of schizophrenia, sex and the presence or absence of first-degree relatives with schizophrenia was investigated in 2,417 inpatients meeting the DSM-III criteria for schizophrenia. The mean age at onset of female schizophrenic patients without a family history of this illness was slightly later than that of any of the other three groups (male familial, female familial and male nonfamilial groups). The female nonfamilial group developed schizophrenia after the age of 25 and 30 more frequently than the male familial group and female familial or male nonfamilial group, respectively.