Sexual Orientation Linked to Handedness

Article excerpt

Palm readers take note: A team of Canadian psychologists suggests that part of understanding sexual orientation may be close at hand. The clue isn't in the bend of the love line or length of the ring finger. It's in which hand you present to the palmist.

The psychologists combined the results of 20 previous studies, both published and unpublished, comparing rates of right-handedness in a total of 23,410 homosexual and heterosexual men and women.

The researchers report in the July PSYCHOLOGICAL BULLETIN that, overall, homosexual adults in the studies were 39 percent more likely than heterosexuals to use their left hand for more activities. The rate was even higher among lesbians, who were nearly twice as likely as heterosexuals to be left- or mixed-handed.

Because hand preference likely has a prenatal origin, the analysis supports the idea that sexual orientation also has early neurobiological roots, says Kenneth J. Zucker of the Centre for Addiction and Mental Health in Toronto and the University of Toronto, an author of the study. The analysis is notable, too, because it reveals a correlate of homosexuality--in this case handedness--that's common to both gay men and lesbians. Many hypotheses posit separate explanations for the sexual preference of each group.

Although the team found a significant correlation, the size of the effect was small, prompting some researchers to downplay the sexuality-southpaw link. The team is "drawing a weak connection between one poorly understood phenomenon and another poorly understood phenomenon," says Simon LeVay, a Los Angeles neuroscientist who in 1991 discovered structural differences in brain anatomy between gay and heterosexual men.

A widely reported paper in the March 30 NATURE by a research team led by psychologist S. Marc Breedlove at the University of California, Berkeley suggested a link between a similar prenatal event and sexual orientation. …