ILLNESS AND ACCIDENTAL INJURY IN YOUNG AND OLDER ADULT LEFT-HANDERS AND RIGHT-HANDERS - IMPLICATIONS FOR GENETIC THEORIES OF HAND PREFERENCE

Three age groups (N = 387) of self-classified left-and right-handers-y oung adults (ages 18 to 30 years), older adults (ages 55 to 74 years) and oldest old adults (ages 75 to 94 years)-answered questions concern ing their health and accident occurrence history. We found no evidence to support the suggestion that left-handers were more likely to suffe r from either major or minor health problems, including categories of illnesses associated with immune disorders. Also, the left-handed grou ps did not display a significantly higher incidence of either major or minor accidental injury, although they indicated that they found comm on cutting implements less easy to use when compared to the responses of right-handers. Left-handed participants in all 3 age groups indicat ed that attempts had been made, typically during their childhood years , to switch their hand preference toward the right side; the highest i ncidence rate of switch reports was among the oldest old adult left-ha nders, with 82.6% reporting hand preference change attempts. Our data are not consistent with models of hand preference formation that state that deviations from genetic right-hand preference are the complete o r partial result of pathological influences (Coren, 1995b). However, o ur data can be incorporated into genetic models that take into account the influences of life experience variables on hand preference format ion (Laland, Kumm, Van Hem, & Feldman, 1995).