Handedness in two generations.

A 14-item questionnaire was administered to tertiary students and their families. The responses of the 508 subjects in the parental generation were compared with those of the 917 younger subjects. For every item significantly fewer older subjects gave left responses. The questionnaire identified more left-handers among subjects than writing hand did, but as only 5.9% of these were classed as left-handed, compared with 11.8% of the younger generation, it seems unlikely that ascertainment was complete in the parental group. Using data from an additional 69 non-right-handers, item analyses indicated that writing and drawing were unsuitable items for older subjects and that, of the items tested, toothbrush and hammer use and pouring would be the best indicators of left-handedness.