Posts Tagged As: Genetics

Another Genetic Link?

Jim Burroway

February 14th, 2014

That’s what a new study from Chicago suggests:

A region of the X chromosome called Xq28 had some impact on men’s sexual behaviour – though scientists have no idea which of the many genes in the region are involved, nor how many lie elsewhere in the genome.

Another stretch of DNA on chromosome 8 also played a role in male sexual orientation – though again the precise mechanism is unclear.

Researchers have speculated in the past that genes linked to homosexuality in men may have survived evolution because they happened to make women who carried them more fertile. This may be the case for genes in the Xq28 region, as the X chromosome is passed down to men exclusively from their mothers.

Michael Bailey, of Northwest University in Chicago, presented his findings at a meeting of the of the American Association for the Advancement of Science yesterday in Chicago. Bailey’s findings have yet to be published. Earlier research by Dean Hamer in 1993 also found that 33 out of 40 gay brothers had inherited similar genetic markers on the Xq28 region of the X chromosome.

The data however suggests that this may not explain homosexuality in all gay men. Some may inherit these markers, while others may be gay due to other factors, including potentially other biological factors such as pre-natal hormones. The data also suggests that even for those who do inherit these markers, genetics is likely not the sole influence on sexuality. For example, identical twins are not carbon copies of each other. For example, they still have unique fingerprints, irises, mole patterns, and many other differences.

“Lesbian mice” created

Timothy Kincaid

July 15th, 2010

In order for a mouse to mate you need some FucM. Fucose mutarotase (abbreviated FucM) is an enzyme that impacts sexual activity in mice. When a gene responsible for FucM is omitted, the developing brains of mice are exposed to extra oestrogen and the female pups exhibit sex-atypical behavior. (New Scientist)

Female mice lacking the gene avoided the advances of males, stopped sniffing male urine and attempted to mate with other females, though their ability to have pups was unaffected.

This is getting some attention. As Fox News asked, “Have Scientists Found the ‘Gay Gene’?

Sure. If you’re a female mouse.

Obviously human sexuality is far more complex than the mating instincts of mice. And it is extremely unlikely that any single gene is going to be found which dictates sexual orientation. But as time goes on we get a clearer picture that biology plays at least some part in the development of sexual orientation.

Simon LeVay, who researches the origins of sexuality, says that the Korean study is not directly relevant to the issue of human sexual orientation. As he points out, it is testosterone not oestrogen that masculinises the human brain, and human AFP doesn’t prevent oestrogen from entering the brain as it does in mice.

“Nevertheless, it is probably only a matter of time before molecular geneticists identify genes that influence sexual orientation in humans,” says LeVay.

It will be fascinating to see the response of conservatives when that time comes.

A Possible Hereditary Model Explaining Homosexuality in Men

Timothy Kincaid

June 18th, 2008

“I say it’s a choice ‘cuz if homoseeeexshality was heriditary then why din’t they all die out? They ain’t got no kids.”

Some people believe that if homosexuality had some genetic contributor then the reduction in average number of children born to gay males would over time cause this gene to become extinct. However a new model challenges this assumption.

From Fox News

In 2004 the researchers studied about 200 Italian families and found that the mothers, maternal aunts and maternal grandmothers of gay men are more fecund, or fruitful, than average.

Recently, they tried to explain their findings with a number of genetic models, and found one that fit the bill.

“This is the first time that a model fits all our empirical data,” said Andrea Camperio-Ciani, an evolutionary psychologist at the University of Padova in Italy who led the study. “These genes work in a sexually antagonistic way — that means that when they’re represented in a female, they increase fecundity, and when they’re represented in a male, they decrease fecundity. It’s a trait that benefits one sex at the cost of the other.”

If the same genes create both homosexuality in men and increased fertility in women, then any losses in offspring that come about from the males would be made up for by the females of the family.

The research results can be found on PLoS ONE

We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait.

UCLA to Study Identical Twins

Timothy Kincaid

May 31st, 2008

twins.png Anti-gays cling to the mantra “there is no gay gene” to comfort them when troubled about their efforts to legislate discrimination. As long as sexual orientation is not genetic then they can claim it is not innate and therefore gay people can be blamed and punished.

Anti-gays know we can’t change our genes, but if they can convince themselves that orientation is brought on by environment, well then it can be reversed and they can insist that gay persons choose to change. And if we don’t, then they have every right to deny us marriage, redress from organized bigotry, the opportunity for housing or employment, and the rights to serve our country, raise our children, and care for our own.

If “there’s no gay gene” and gays choose to stay “in the lifestyle”, then anti-gays can convince themselves that they aren’t monsters, but that we are.

Hey, we all have to find a way to sleep at night.

One of the “evidences” that anti-gays use to insist that sexual orientation is not based in genetics is the fact that not all identical twins have the same orientation. As Focus on the Family’s Melissa Fryrear puts it

The third major study trumpeted as “proof” of homosexuality’s genetic link was also conducted in 1991 by psychologist Michael Bailey and psychiatrist Richard Pillard. Using pairs of brothers — identical twins, non-identical twins, biological brothers, and adopted brothers — Bailey and Pillard attempted to show that homosexuality occurs more frequently among identical twins than fraternal twins.

Again, what the majority of people do not know, and what the media did not accurately report, is that this study actually provides support for environmental factors versus genetics! If homosexuality were in the genetic code, then both of the twins would have been homosexual 100 percent of the time, yet this was not the case.

Most researchers see the differences of orientation matching (50% in identical twins and 20% in fraternal twins compared to a general population rate of probably less than 6%) as an indication that genetics are a factor. But anti-gays magically find just the opposite. Since Melissa’s research credentials are, well, not particularly solid, she relies on NARTH’s Neil Whitehead to back up her assertions.

Identical twins have identical genes. If homosexuality was a biological condition produced inescapably by the genes (e.g. eye color), then if one identical twin was homosexual, in 100% of the cases his brother would be too. But we know that only about 38% of the time is the identical twin brother homosexual. Genes are responsible for an indirect influence, but on average, they do not force people into homosexuality. This conclusion has been well known in the scientific community for a few decades but has not reached the general public. Indeed, the public increasingly believes the opposite.

Fryrear may be excused for having but a layman’s understanding of genetics. But when Whitehead implies that genetics can be disregarded he is either demonstrating a willful ignorance or is cynically seeking to play on the public’s lack of expertise.

Genetic influence is not limited to a gene’s presence. Identical genes do not behave identically. And a research team at the University of California at Los Angeles (UCLA) Center for Gender-Based Biology is setting out to study just what role genes play in determining sexual attraction. Out in America reports

Identical twins provide a unique model to study the role of gene regulation: “Both twins have the same genes, but they might use these genes differently,” says Bocklandt. “And that difference in gene use could explain the difference in sexual orientation.”

“If we can identify specific genes that are ‘turned off’ or ‘turned on’ among our gay and straight twins, we will have excellent genetic targets for further investigation with respect to sexual orientation,” Bocklandt adds.

Study researchers will measure the chemical signal attached to the DNA that controls if and when a gene is turned on and off. Utilizing novel DNA-chip technology, large parts of the human genome can be screened for differences in gene regulation between the twins. “Because identical twins have the same DNA sequence, we can study a ‘gay genome’ and a ‘straight genome’ within one single genetic background, and that’s extremely powerful,” says Bocklandt.

The study is headed by Drs. Eric Vilain, Cisco Sanchez, and Sven Bocklandt. Drs. Vilain and Bocklandt were part of the team that observed the extreme skewing of x chromosome inactivation in the mothers of gay men. Bocklandt also worked with Hamer on his earlier gene research (which was horribly misreported) and is one of the “gay sheep guys” who researched the variances in the brains of same-sex attracted rams. These researchers are at the very forefront of studying how genetics and orientation interplay.

This research promises to add to the growing knowledge on what does and does not contribute to sexual orientation. It may help understand whether genes can be solely, significantly, or only minimally responsible for the sex to which each of us are attracted. And while I doubt that a “gay gene” that indisputably determines orientation is likely to be the result, additional information in this field of study is very welcome.

The team currently has about 20 sets of mixed-orientation identical twins and is seeking to double that size. If you are an identical twin whose sibling does not share your orientation, check out the study to see if you would like to participate.

If you are not an identical twin but are a gay man with a gay brother, please consider contributing to the work being performed by Dr. Sanders at Northwestern University.

‘Family Guy’ to Explore Gay Gene and Ex-Gay Therapy

Timothy Kincaid

January 30th, 2008

family-guy.jpgIn an interview with the Advocate, Seth MacFarlane, creator of The Family Guy discusses an upcoming episode:

What can we expect from the as yet unscheduled episode titled “Family Gay”?

That has to do with Peter being injected with the gay gene as part of a scientific experiment to determine whether or not it’s a learned trait or something that you’re born with. The good news is that at the end of the episode we establish that it’s the latter. Basically, Peter’s in a gay relationship for an episode and winds up in one of those straight camps.

Undoubtedly this will be presented with their usual tact and unerring good taste.

Read the full interview here.

It’s in the Blood

Timothy Kincaid

January 13th, 2008

A reader drew my attention to a study released last month that did not get much press (if any). Using a sample of over 7,000 participants, sociologists at Minot State University in North Dakota identified a correlation between sexual orientation and both blood type and Rh factor.

Heterosexual males and females exhibited statistically identical frequencies of the A blood type, while gay men exhibited a relatively low incidence and lesbians had a relatively high incidence (p < .05). In the case of the Rh factor, unusually high proportions of homosexuals of both sexes were Rh- when compared to heterosexuals (p < .06). The findings suggest that a connection may exist between sexual orientation and genes both on chromosome 9 (where blood type is determined) and on chromosome 1 (where the Rh factor is regulated).

This study adds to the now convincing argument that the bases of orientation lie at least in part in biology. Someone needs to tell Dr. Dobson that regardless of the amount of time a father spends doting on his son, it isn’t going to affect his blood type or his Rh factor.


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