[Paleopsych] BH: "Gay Genes" May Increase Fertility

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"Gay Genes" May Increase Fertility
http://www.betterhumans.com/Print/index.aspx?ArticleID=2004-10-13-4

Findings help resolve evolutionary paradox in supporting genetic basis of
homosexuality

    Betterhumans Staff
    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
    genes"

    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
    [1]University of Padova have found evidence that genetic factors
    underlying male [2]homosexuality also increase fertility in females.

    The findings help resolve an [3]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
    survive.

    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 [4]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 [5]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 [6]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 [7]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 [8]Proceedings of the Royal
    Society B: Biological Sciences.

References

    1. http://www.unipd.it/
    2. http://www.wikipedia.org/wiki/Homosexuality
    3. http://www.wikipedia.org/wiki/Evolution
    4. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8332896
    5. http://www.betterhumans.com/News/news.aspx?ArticleID=2003-10-20-7
    6. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8540587
    7. http://www.wikipedia.org/wiki/X_chromosome
    8. http://www.pubs.royalsoc.ac.uk/proc_bio_homepage.shtml