Handedness is interesting because we can see patterns in people, but don’t know what makes me right handed and some other person left handed (and we won’t even get into the ambidextrous). Current theories on handedness include genetics, birth stress, ultrasound, and prenatal testosterone. We also know body asymmetry correlates with gendered cognition, so we surmise there may be a relationship between cognition and handedness.
The other confusing thing is that varying studies have come up with conflicting results. One study only found the effect in gay women, while another only found it in gay men. Adding further confusion, the more older brothers a boy has, the more likely he is to be gay, but this is only true for right-handed males. Left-handed males are only more likely to be gay if they have no older brothers. Right-handed males without older brothers, and left-handed males with older brothers, were homosexual at about the same rate.
Clearly something is going on here, but more study is figure out exactly what!
- Gay Men: Tend towards left-handedness. No older brother effect for right-handed gay men.
- Lesbians: Tend towards left-handedness.
- Lalumière ML, Blanchard R, Zucker KJ., Sexual orientation and handedness in men and women: a meta-analysis. Psychol Bull. 2000 Jul;126(4):575-92. A meta-analysis of 20 previous studies showing gay people are somewhat more left handed than straight people.
- Mustanski, B. S., Bailey, J. M., & Kaspar, S. (2002). Dermatoglyphics, handedness, sex, and sexual orientation. Archives of Sexual Behavior, 31, 113–122. Found that homosexual women to be more left handed that straight women, but did not find the same effect in heterosexual and homosexual men.
- Lippa, R. A. (2003). Handedness, sexual orientation, and gender-related personality traits in men and women. Archives of Sexual Behavior, 32 103–114. Found homosexual men more left handed than heterosexual men, but did not find the same effect in women.
- Blanchard, R., Cantor, J. M., Bogaert, A. F., Breedlove, S. M., & Ellis, L. (2006). Interaction of fraternal birth order and handedness in the development of male homosexuality. Hormones and Behavior, 49, 405–414. Found the older brother effect in handedness.
This article is part of a series, Written on the Body, exploring the correlations between our body structures and sexual attraction.