Hand dominance of parents and other relatives of autistic children.

Hand preferences of 219 mothers and 186 fathers of autistic children were assessed using the Annett Handedness questionnaire. Subgroups of 54 mothers and 57 fathers with a family history of language-related developmental disorders were identified. Parents also reported the handedness of other relatives. Mothers (but not fathers) in the main group were significantly more likely to be consistently right-handed than females in the general population, but this was not specifically associated with a family history of language problems. There was no evidence of an increased incidence of consistent left-handedness in either the whole group of parents or the subgroups. Reported handedness of other relatives showed no abnormal distribution in relation to a comparison group. The findings are discussed in relation to theories about genetic factors in language-related developmental disorders in general, and autism in particular.