Two Canadian researchers have found a link between the number of ridges in fingerprints and male homosexuality, adding to the theory that sexual orientation is determined before birth.
The researchers, working at the University of Western Ontario, compared the number of tiny ridges on the fingertips of 66 homosexual men with the fingerprint patterns of 182 heterosexual men.Thirty percent of the homosexual men showed more ridges on their left hands than their right, while only 14 percent of the heterosexual men showed the same pattern.
Most men and women have more ridges in the fingerprints of their right hands. Fingerprints are completely developed in human fetuses by about the 16th week after conception.
"This certainly suggests sexual orientation is somehow determined by prenatal events," said researcher Doreen Kimura.
Kimura and the study's lead author, graduate student Jeffrey Hall, said the fingerprint patterns are not distinctive to gay men or a marker for homosexuality. Most homosexual men show the more typical pattern of more ridges on the right hand, they noted.
"What we found is a statistically significant difference between groups of heterosexual and homosexual men," Kimura said.
Roger Gorski, a UCLA neurobiologist who has done extensive research on sexual differentiation, called the study "another suggestion that there's a biological component to sexuality." But he said he had some trouble with making the connection between ridges on fingers and sexual orientation.
"The way I like to summarize it is sexual orientation is a multifaceted behavior and it's unlikely that one gene, that one hormone, that one environmental experience - or that one fingerprint - is going to be the explanation for everything," he said.