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Handedness and sexual orientation
1Department of Psychiatry, Cambridge Hospital/Harvard Medical School.
Journal of Clinical and Experimental Neuropsychology
|October 1, 1994
Summary
Non-heterosexual individuals exhibit reduced right-handedness compared to heterosexuals, suggesting a link between sexual orientation and handedness. This finding supports theories of prenatal hormonal influences on both traits.
Area of Science:
- Neuroscience
- Human Sexuality
- Behavioral Genetics
Background:
- Approximately 90% of the population is right-handed, a phenomenon termed 'right shift'.
- Previous research suggests potential links between non-right-handedness and non-heterosexual orientations.
Purpose of the Study:
- To investigate handedness distribution differences between heterosexual and non-heterosexual individuals with a homosexual/bisexual first-degree relative.
- To explore the relationship between sexual orientation and handedness.
Main Methods:
- A validated five-category self-assessment handedness questionnaire was used.
- Participants included 141 non-heterosexuals and 260 heterosexuals with a homosexual/bisexual first-degree relative.
Main Results:
- Non-heterosexuals demonstrated a significant reduction in right shift compared to heterosexuals.
- Sexual orientation was found to be a weak predictor of handedness.
- Findings align with previous studies by Lindesay (1987) and Becker et al. (1989).
Conclusions:
- The results indirectly support the Geschwind and Galaburda hypothesis linking sexual orientation and handedness, potentially via prenatal testosterone exposure.
- The study highlights the interconnectedness of genetic and hormonal influences and challenges non-heterosexually biased assumptions.