Study seeks to find genetic roots for homosexuality

[amalgamate]

Gay brothers may hold genetic clues
Study seeks scientific explanation for roots of homosexuality


Updated: 12:59 p.m. PT Oct 15, 2007
CHICAGO - Julio and Mauricio Cabrera are gay brothers who are convinced their sexual orientation is as deeply rooted as their Mexican ancestry.

They are among 1,000 pairs of gay brothers taking part in the largest study to date seeking genes that may influence whether people are gay. The Cabreras hope the findings will help silence critics who say homosexuality is an immoral choice.

If fresh evidence is found suggesting genes are involved, perhaps homosexuality will be viewed as no different than other genetic traits like height and hair color, said Julio, a student at DePaul University in Chicago.

Adds his brother, “I think it would help a lot of folks understand us better.”

The federally funded study, led by Chicago area researchers, will rely on blood or saliva samples to help scientists search for genetic clues to the origins of homosexuality. Parents and straight brothers also are being recruited.

While initial results aren’t expected until next year — and won’t provide a final answer — skeptics are already attacking the methods and disputing the presumed results.

Previous studies have shown that sexual orientation tends to cluster in families, though that doesn’t prove genetics is involved. Extended families may share similar child-rearing practices, religion and other beliefs that could also influence sexual orientation.

Research involving identical twins, often used to study genetics since they share the same DNA, has had mixed results.

One widely cited study in the 1990s found that if one member of a pair of identical twins was gay, the other had a 52 percent chance of being gay. In contrast, the result for pairs of non-twin brothers, was 9 percent. A 2000 study of Australian identical twins found a much lower chance.

No single 'gay gene'
Dr. Alan Sanders of Evanston Northwestern Healthcare Research Institute, the lead researcher of the new study, said he suspects there isn’t one so-called “gay gene.”

It is more likely there are several genes that interact with nongenetic factors, including psychological and social influences, to determine sexual orientation, said Sanders, a psychiatrist.

Still, he said, “If there’s one gene that makes a sizable contribution, we have a pretty good chance” of finding it.

Many gays fear that if gay genes are identified, it could result in discrimination, prenatal testing and even abortions to eliminate homosexuals, said Joel Ginsberg of the Gay and Lesbian Medical Association.

However, he added, “If we confirm that sexual orientation is an immutable characteristic, we are much more likely to get the courts to rule against discrimination.”

There is less research on lesbians, Sanders said, although some studies suggest that male and female sexual orientation may have different genetic influences.

His new research is an attempt to duplicate and expand on a study published in 1993 involving 40 pairs of gay brothers. That hotly debated study, wrongly touted as locating “the gay gene,” found that gay brothers shared genetic markers in a region on the X chromosome, which men inherit from their mothers.

That implies that any genes influencing sexual orientation lie somewhere in that region.

Previous attempts to duplicate those results failed. But Sanders said that with so many participants, his study has a better chance of finding the same markers and perhaps others on different chromosomes.

If these markers appear in gay brothers but not their straight brothers or parents, that would suggest a link to sexual orientation. The study is designed to find genetic markers, not to explain any genetic role in behavior.

And Sanders said even if he finds no evidence, that won’t mean genetics play no role; it may simply mean that individual genes have a smaller effect.

Skeptics include Stanton Jones, a psychology professor and provost at Wheaton College in Wheaton, Ill. An evangelical Christian, Jones last month announced results of a study he co-authored that says it’s possible for gays to “convert” — changing their sexual orientation without harm.

Jones said his results suggest biology plays only a minor role in sexual orientation, and that researchers seeking genetic clues generally have a pro-gay agenda that will produce biased results.

Sanders disputed that criticism.

“We do not have a predetermined point we are trying to prove,” he said. “We are trying to pry some of nature’s secrets loose with respect to a fundamental human trait.”

Jones acknowledged that he’s not a neutral observer. His study involved 98 gays “seeking help” from Exodus International, a Christian group that believes homosexuals can become straight through prayer and counseling. Exodus International funded Jones’ study.

The group’s president, Alan Chambers, said he is a former homosexual who went straight and believes homosexuality is morally wrong.

Critics espouse 'freedom to choose'
Even if research ultimately shows that genetics play a bigger role, it “will never be something that forces people to behave in a certain way,” Chambers said. “We all have the freedom to choose.”

The Cabrera brothers grew up in Mexico in a culture where “being gay was an embarrassment,” especially for their father, said Mauricio, 41, a car dealership employee from Olathe, Kan.

They had cousins who were gay, but Mauricio said he still felt he had to hide his sexual orientation and he struggled with his “double life.” Julio said having an older brother who was gay made it easier for him to accept his sexuality.

Jim Larkin, 54, a gay journalist in Flint, Mich., said the genetics study is a move in the right direction.

Given the difficulties of being gay in a predominantly straight society, homosexuality “is not a choice someone would make in life,” said Larkin, who is not a study participant.

He had two brothers who were gay. One died from AIDS; the other committed suicide. Larkin said he didn’t come out until he was 26.

“I fought and I prayed and I went to Mass and I said the rosary,” Larkin said. “I moved away from everybody I knew ... thinking maybe this will cause the feelings to subside. It doesn’t.”

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U.S. researchers find evidence that homosexuality linked to genetics

December 1, 2008 -- Compared to straight men, gay men are more likely to be left-handed, to be the younger siblings of older brothers, and to have hair that whorls in a counterclockwise direction.

US researchers are finding common biological traits among gay men, feeding a growing consensus that sexual orientation is an inborn combination of genetic and environmental factors that largely decide a person's sexual attractions before they are born.

Such findings - including a highly anticipated study this winter - would further inform the debate over whether homosexuality is innate or a choice, an undercurrent of California's recent Proposition 8 campaign in which television commercials warned that "schools would begin teaching second-graders that boys could marry boys", suggesting homosexuality would then spread.

Some scientists say the political and moral debate over same-sex marriage frequently strayed from established scientific evidence, including comments by Republican vice-presidential candidate Sarah Palin that homosexuality is "a choice" and "a decision".

Until 2007, CNN polls had found that a majority of Americans believed gay people could change their sexual orientation if they chose to; it was only last year that a majority for the first time said homosexuality was an inborn trait.

Christian groups such as Exodus International argue "that homosexuals who desire to change can do so". One prominent psychiatrist, Dr Robert Spitzer of Columbia University, found controversial evidence that therapy can cause some gay people to change to a heterosexual orientation, although the study concluded that a "complete change" was uncommon.

While sexual behaviour may be chosen, the preponderance of researchers say attraction is dictated by biology, with no demonstrated contribution from social factors such as parenting or other factors after birth.

A host of studies since the mid-1990s have found common biological traits between gay men, including left-handedness and the direction of hair whorls. The likelihood that if one identical twin is gay, the other will be also be gay is much higher than the "concordance" of homosexuality between fraternal twins, indicating that genes play a role in sexual orientation, but are not the entire cause.

"In the past decade, I think the pendulum has swung more toward biological theory and biological causes," said Richard Lippa, a psychology professor at California State University-Fullerton, who has studied hair patterns and other biological traits in gay men.

Sven Bocklandt, a geneticist at the David Geffen school of medicine at UCLA, is bewildered by the argument that people choose their sexual attraction. He said that virtually every animal species that has been studied - from sheep to fruit flies - has a small minority of individuals who demonstrate homosexual activity.

"I really believe the reason most humans are straight is the same reason that most crocodiles are straight, and the same reason most whales are straight," Bocklandt said. "Nature would not leave something so important for reproduction, for the survival of the species, to coincidence."

Less understood is the degree to which sexual orientation is determined by genes or environmental factors, such as hormones or immunological factors that may act on a foetus. What scientists call "the fraternal birth order effect", the fact that each successive boy born to the same mother has a greater chance of being gay, may be due to an increasing immunological response by a mother's body to each male foetus in her womb.

Long discredited are theories that parenting - one mid-20th century theory held that boys raised by a domineering mother with a distant father were more likely to be gay - has anything to do with sexual orientation.

Evidence of that, said Michael Bailey, a professor of psychology at Northwestern University in Illinois, comes from studies of genetically male infants born with malformed or ambiguous genitals. In many such cases, surgeons would construct a vagina, and instruct parents to raise the child as a girl, with no knowledge of his medical history.

As adults, those prenatally male/postnatally female people were virtually all attracted to women, Bailey said.

"If you can't make a male attracted to other males by cutting off his penis, castrating him and rearing him as a girl, then how likely is any social explanation of male homosexuality?" he said.

Researchers are eagerly awaiting a DNA study of male siblings with at least one gay brother by Bailey and other scientists at Northwestern University due in early 2009, because it may shed light on the role genetics plays in sexual attraction.

By researching 800 sets of brothers, by far the largest study of its type, the Northwestern study is searching for the specific genes that influence some brothers to be gay and others to be heterosexual.

Women may have more fluidity of sexual expression than men, but that doesn't mean they don't have a specific sexual orientation, said Lisa Diamond, a professor of psychology and gender studies at the University of Utah who studies female sexual orientation.

One explanation is that women's sexual behaviour is driven more by relationships.

For some women, "your sexual orientation does not provide the last word on the sorts of behaviours and identities you might experience in your lifetime," Diamond said.

"Some lesbian women are predominantly attracted to women, but some of them have found themselves becoming incredibly close to their best male friends, sometimes having sex with them. It does not make them straight. It's not, since you had a one-night stand with your male friend, that you can choose to become straight."

[amalgamate]

December 1, 2008 -- Compared to straight men, gay men are more likely to be left-handed, to be the younger siblings of older brothers, and to have hair that whorls in a counterclockwise direction.

yea and if they've got brown eyes and blond hair, they're uncle's cousins's nephew would be gay as well.