Parental age and birth order in homosexual patients: a replication of Slater's study.

Parental age (at patient's birth) and birth order were studied in 623 male and 89 female patients diagnosed as homosexual, who were born in England and Wales and first attended the Maudsley Hospital between the years 1961-1975. For male patients, mean parental ages were significantly higher than expectation, and mean birth order was significantly later. Regression analysis indicated that the raised fathers' age was probably of more aetiological importance than the raised mothers' age. The results confirm those of previous studies. The female patients did not show a raised parental age or late birth order.