Left-handedness, homosexuality, HIV infection and AIDS.

Left-handedness was assessed in a large sample of male homosexuals and male and female heterosexuals, some of whom had been tested for HIV infection, and others of whom had AIDS. No association was found between left-handedness and homosexuality, although there was an excess of left-handers in subjects who had been tested for HIV infection (irrespective of whether the test was negative or positive). This result can be interpreted in three possible ways: as a response bias on the part of left-handers who were aware of the Geschwind hypothesis that left-handedness may confer a vulnerability to AIDS; as due to left-handedness being associated with AIDS infection and the incidence in AIDS patients being artefactually low due to an excess mortality in left-handed AIDS patients; and as left-handers showing both an increased vulnerability of HIV infection and a reduced likelihood of progression of HIV infection into AIDS. Our data are unable to distinguish between these hypotheses. Left-handedness was not associated with any of seventeen specific conditions, including migraine, dyslexia and stuttering.