I'm sure you wanted to know why there were so many gays when they are
not reproducing. ;)

I'm sure you wanted to know why there were so many gays when they are
not reproducing. ;)

SURVIVAL OF GENETIC HOMOSEXUAL TRAITS EXPLAINED
By Andy Coghlan
New Scientist
October 13, 2004

http://www.newscientist.com/news/news.jsp?id=ns99996519

Italian geneticists may have explained how genes apparently linked to
male
homosexuality survive, despite gay men seldom having children. Their
findings also undermine the theory of a single "gay gene".

The researchers discovered that women tend to have more children when
they
inherit the same -- as yet unidentified -- genetic factors linked to
homosexuality in men. This fertility boost more than compensates for
the
lack of offspring fathered by gay men, and keeps the "gay" genetic
factors
in circulation.

The findings represent the best explanation yet for the Darwinian
paradox
presented by homosexuality: it is a genetic dead-end, yet the trait
persists
generation after generation.

"We have finally solved this paradox," says Andrea Camperio-Ciani of
the
University of Padua. "The same factor that influences sexual
orientation in
males promotes higher fecundity in females."

Relative differences

Camperio-Ciani's team questioned 98 gay and 100 straight men about
their
closest relatives -- 4600 people in total. They found that female
relatives
of gay men had more children on average than the female relatives of
straight men. But the effect was only seen on their mother's side of
the
family.

Mothers of gay men produced an average of 2.7 babies compared with 2.3
born
to mothers of straight men. And maternal aunts of gay men had 2.0
babies
compared with 1.5 born to the maternal aunts of straight men.

"This is a novel finding," says Simon LeVay, a neuroscientist and
commentator on sexuality at Stanford University in California. "We
think of
it as genes for 'male homosexuality', but it might really be genes for
sexual attraction to men. These could predispose men towards
homosexuality
and women towards 'hyper-heterosexuality', causing women to have more
sex
with men and thus have more offspring."

Camperio-Ciani stresses that whatever the genetic factors are, there
is no
single gene accounting for his observations. And the tendency of the
trait
to be passed through the female line backs previous research
suggesting that
some of the factors involved are on the male "X" chromosome, the only
sex
chromosome passed down by women. "It's a combination of something on
the X
chromosome with other genetic factors on the non-sex chromosomes," he
says.

Immune system

Helen Wallace, of the UK lobby group GeneWatch, welcomes the new
research
that moves away from the controversial single-gene theory for
homosexuality.
"But it's worth noting that the data on the sexuality of family
members may
be unreliable, so more studies are likely to be needed to confirm
these
findings," she says.

Even if the maternal factors identified by Camperio-Ciani's team are
linked
with male homosexuality, the research team's calculations suggest they
account for only about 14% of the incidence.

Their findings also support earlier findings that when mothers have
several
sons, the younger ones are progressively more likely to be gay. This
might
be due to effects changes to the mother's immune system with each son
they
carry.

But Camperio-Ciani calculates the contribution of this effect to male
homosexuality at 7% at most. So together, he says, the "maternal" and
"immune" effects only account for 21% of male homosexuality, leaving
79% of
the causation still a mystery.

This leaves a major role for environmental factors, or perhaps more
genetic
factors. "Genes must develop in an environment, so if the environment
changes, genes go in a new direction," he says. "Our findings are only
one
piece in a much larger puzzle on the nature of human sexuality."

Journal reference: Proceedings of the Royal Society B: Biological
Sciences
(DOI: 10.1098/rspb.2004)

I'm sure you wanted to know why there were so many gays when they are
not reproducing. ;)


SURVIVAL OF GENETIC HOMOSEXUAL TRAITS EXPLAINED
By Andy Coghlan
New Scientist
October 13, 2004

http://www.newscientist.com/news/news.jsp?id=ns99996519

Italian geneticists may have explained how genes apparently linked to
male
homosexuality survive, despite gay men seldom having children. Their
findings also undermine the theory of a single "gay gene".

The researchers discovered that women tend to have more children when
they
inherit the same -- as yet unidentified -- genetic factors linked to
homosexuality in men. This fertility boost more than compensates for
the
lack of offspring fathered by gay men, and keeps the "gay" genetic
factors
in circulation.

The findings represent the best explanation yet for the Darwinian
paradox
presented by homosexuality: it is a genetic dead-end, yet the trait
persists
generation after generation.

"We have finally solved this paradox," says Andrea Camperio-Ciani of
the
University of Padua. "The same factor that influences sexual
orientation in
males promotes higher fecundity in females."

Relative differences

Camperio-Ciani's team questioned 98 gay and 100 straight men about
their
closest relatives -- 4600 people in total. They found that female
relatives
of gay men had more children on average than the female relatives of
straight men. But the effect was only seen on their mother's side of
the
family.

Mothers of gay men produced an average of 2.7 babies compared with 2.3
born
to mothers of straight men. And maternal aunts of gay men had 2.0
babies
compared with 1.5 born to the maternal aunts of straight men.

"This is a novel finding," says Simon LeVay, a neuroscientist and
commentator on sexuality at Stanford University in California. "We
think of
it as genes for 'male homosexuality', but it might really be genes for
sexual attraction to men. These could predispose men towards
homosexuality
and women towards 'hyper-heterosexuality', causing women to have more
sex
with men and thus have more offspring."

Camperio-Ciani stresses that whatever the genetic factors are, there
is no
single gene accounting for his observations. And the tendency of the
trait
to be passed through the female line backs previous research
suggesting that
some of the factors involved are on the male "X" chromosome, the only
sex
chromosome passed down by women. "It's a combination of something on
the X
chromosome with other genetic factors on the non-sex chromosomes," he
says.

Immune system

Helen Wallace, of the UK lobby group GeneWatch, welcomes the new
research
that moves away from the controversial single-gene theory for
homosexuality.
"But it's worth noting that the data on the sexuality of family
members may
be unreliable, so more studies are likely to be needed to confirm
these
findings," she says.

Even if the maternal factors identified by Camperio-Ciani's team are
linked
with male homosexuality, the research team's calculations suggest they
account for only about 14% of the incidence.

Their findings also support earlier findings that when mothers have
several
sons, the younger ones are progressively more likely to be gay. This
might
be due to effects changes to the mother's immune system with each son
they
carry.

But Camperio-Ciani calculates the contribution of this effect to male
homosexuality at 7% at most. So together, he says, the "maternal" and
"immune" effects only account for 21% of male homosexuality, leaving
79% of
the causation still a mystery.

This leaves a major role for environmental factors, or perhaps more
genetic
factors. "Genes must develop in an environment, so if the environment
changes, genes go in a new direction," he says. "Our findings are only
one
piece in a much larger puzzle on the nature of human sexuality."

Journal reference: Proceedings of the Royal Society B: Biological
Sciences
(DOI: 10.1098/rspb.2004)