[Paleopsych] BH: "Gay Genes" May Increase Fertility
checker at panix.com
Thu Oct 14 14:57:48 UTC 2004
"Gay Genes" May Increase Fertility
Findings help resolve evolutionary paradox in supporting genetic basis of
10/13/2004 4:22 PM
Genetic connection: Female relatives of gay men have been found more
fertile, providing a solution to the evolutionary puzzle of "gay
Mothers of homosexual men and their female relatives appear to be more
fertile, providing support for a genetic basis of homosexuality by
explaining how "gay genes" survive.
Italian researcher Francesca Corna and colleagues from the
University of Padova have found evidence that genetic factors
underlying male homosexuality also increase fertility in females.
The findings help resolve an evolutionary puzzle surrounding
homosexuality's genetic underpinnings. According to evolutionary
theory, traits that reduce an organism's reproductive success would
gradually disappear as creatures with the traits die out. But if women
carrying gay genes are more fertile, their increased reproduction
could compensate for nonreproductive children and allow gay genes to
X marks the spot
Since the early 1990s, research has strongly suggested underlying
biological and genetic factors influencing homosexuality.
In 1993, US researchers reported finding evidence that
homosexuality was passed from mother to son, although other
researchers couldn't replicate the results and questioned the finding.
Last year, researchers discovered more than 50 genes linked to the
organization of male and female brains, supporting the notion that
homosexuality has biological origins.
Findings have also suggested that homosexual males tend to be
younger siblings in families with many male children.
Such findings have led researchers to suggest that after birthing many
heterosexual males, some mothers may experience biological changes
that cause them to birth homosexual males.
Indeed, evidence has suggested that gay genes lie on part of the X
chromosome that mothers pass to their offspring.
Relatively more reproductive
For their study, Corna and colleagues looked at 98 homosexual and 100
heterosexual men and their relatives in a study that involved more
than 4,600 people.
They found that female relatives of the homosexual men's mothers had
more offspring than female relatives of their fathers. This suggested
that women who pass on gay genes to male offspring are more fertile.
The theory was supported by the fact that female relatives of the
heterosexual men's parents weren't as fertile.
Still, the researchers estimate that the maternal effect accounted for
just 14% of homosexuality and that birth order accounted for just
6.7%. This means that about 79% of homosexuality's origin is unknown,
leaving room for many other influences, both biological and cultural.
"It is clear that our findings, if confirmed by further research, are
only one piece in a much larger puzzle on the nature of human
sexuality," the researchers say.
The research is reported in the journal Proceedings of the Royal
Society B: Biological Sciences.
More information about the paleopsych