Incest and mental handicap.

This is probably the first retrospective study of an adult mentally handicapped population of incestuous parentage. Eleven known incestuous unions were identified with 38 offspring, of whom 15 were admitted to the Stoke Park group of hospitals. Incest and its legal definition in different societies are considered. The effects of close inbreeding on mortality, morbidity, mental function and adoption are examined. The study also reaffirms that incest is one of the causes of mental handicap in a high percentage of offspring.