What do the new ‘gay gen’ tell about sexual orientatn? | New Scientist

Contents:

• WHY ARE PEOPLE GAY? GAY BY CHOICE OR IS BEG GAY GEIC?
• THERE IS NO ‘GAY GENE.’ THERE IS NO ‘STRAIGHT GENE.’ SEXUALY IS JT PLEX, STUDY NFIRMS
• SCIENTISTS MAY HAVE FALLY UNLOCKED PUZZLE OF WHY PEOPLE ARE GAY
• IS BEG GAY GEIC?
• GAY GEICS
• IS A PERSON ‘BORN GAY’, OR IS BEG GAY A LEARNED BEHAVR?
• THE 'GAY GENE' IS A MYTH BUT BEG GAY IS 'NATURAL,' SAY SCIENTISTS
• THE LIFE OF THE GAY GENE: OM HYPOTHETIL GEIC MARKER TO SOCIAL REALY
• WHAT DO THE NEW ‘GAY GEN’ TELL ABOUT SEXUAL ORIENTATN?
• THERE’S NO ONE ‘GAY GENE,’ BUT GEICS ARE LKED TO SAME-SEX BEHAVR, NEW STUDY SAYS

WHY ARE PEOPLE GAY? GAY BY CHOICE OR IS BEG GAY GEIC?

It very much appears that same-sex sexual attractn is not a choice but actg on is; so if you fe gay as the mere prence of same-sex attractn, then om everythg we unrstand, beg gay is not a choice. However, blogists have documented homosexual behavr more than 450 speci, argug that same-sex behavr is not an unnatural choice, and may fact play a val role wh populatns. So-lled genome-wi associatn studi intified a gene lled SLITRK6, which is active a bra regn lled the diencephalon that differs size between people who are homosexual or heterosexual.

While there is no sgle “gay gene, ” there is overwhelmg evince of a blogil basis for sexual orientatn that is programmed to the bra before birth based on a mix of geics and prenatal ndns, none of which the fet choos. Humans have tried to unrstand human sexualy for centuri — and geics rearchers joed the ay the early 1990s after a seri of studi on tws suggted homosexualy ran fai. “As a teenager tryg to unrstand myself and unrstand my sexualy, I looked at the ter for “the gay gene” and obvly me across Xq28, ” said Fah Sathirapongsasuti, a study -thor and senr scientist at 23andMe, which he joked once led him to believe he hered his gayns om his mother.

The rearchers had members of the same-sex muny review the study’s sign and language, and they adm that their termology and fns for gay, lbian and heterosexual do not reflect the full nature of the sexualy ntuum. “[Our study] unrsr an important role for the environment shapg human sexual behavr and perhaps most importantly there is no sgle gay gene but rather the ntributn of many small geic effects sttered across the genome, ” Neale said.

THERE IS NO ‘GAY GENE.’ THERE IS NO ‘STRAIGHT GENE.’ SEXUALY IS JT PLEX, STUDY NFIRMS

A group of scientists suggted Tuday that homosexuals get that tra om their oppose-sex parents: A lbian will almost always get the tra om her father, while a gay man will get the tra om his heredary lk of homosexualy has long been tablished, but scientists knew was not a strictly geic lk, bee there are many pairs of intil tws who have differg sexuali. Scientists om the Natnal Instute for Mathematil and Blogil Synthis say homosexualy seems to have an epigeic, not a geic thought to have some sort of heredary lk, a group of scientists suggted Tuday that homosexualy is lked to epi-marks — extra layers of rmatn that ntrol how certa gen are exprsed. In homosexuals, the epi-marks aren't erased — they're passed om father-to-dghter or mother-to-son, explas William Rice, an evolutnary blogist at the Universy of California Santa Barbara and lead thor of the study.

SCIENTISTS MAY HAVE FALLY UNLOCKED PUZZLE OF WHY PEOPLE ARE GAY

"There is pellg evince that epi-marks ntribute to both the siary and dissiary of fay members, and n therefore feasibly ntribute to the observed faial herance of homosexualy and s low nrdance between [intil] tws, " Rice and his team created a mathematil mol that explas why homosexualy is passed through epi-marks, not geics. Evolutnarily speakg, if homosexualy was solely a geic tra, scientists would expect the tra to eventually disappear bee homosexuals wouldn't be expected to reproduce.

IS BEG GAY GEIC?

But bee the epi-marks provi an evolutnary advantage for the parents of homosexuals: They protect fathers of homosexuals om unrexposure to ttosterone and mothers of homosexuals om overexposure to ttosterone while they are gtatn. "The epi-marks protect fathers and mothers om excs or unrexposure to ttosterone — when they rry over to oppose-sex offsprg, n e the masculizatn of femal or the femizatn of mal, " Rice says, which n lead to a child beg gay.

GAY GEICS

Rice not that the markers are "highly variable" and that only strong epi-marks will rult a homosexual scientists have long spected some sort of geic lk, Rice says studi attemptg to expla why people are gay have been few and far between. " Homosexual behavr has been observed black swans, pengus, sheep, and other animals, he 's mol still needs to be tted on real-life parent-offsprg pairs, but he says this epigeic lk mak more sense than any other explanatn, and that his team has mapped out a way for other scientists to tt their work.

Those who nsir beg gay a disadvantage life (which still is, certa societi), might regard gay people differently if they knew that beg gay was an hered tra, rather than a nsequence of life events, such as a particular type of upbrgg, or mixg wh certa sorts of iends or even a liberate cisn. An early study claimed that if one pair of (male) intil tws (who have intil geic patterns) was gay, there was a 100 percent chance of the other one also beg gay. It was quickly shown that, fact, the real chance of two intil tws beg gay was around 40-50 percent, whereas was ls non-intil on, though still somewhat greater than the general populatn.

“The people participatg our study are terted ntributg to this kd of scientific knowledge and want to unrstand at least part of how they me to be the way they are, ” Sanrs search for ‘gay gen’ go back to 1993, when a US team led by Dr Dean Hamer scribed a regn of DNA loted on the X chromosome lled Xq28. “Conservative, right-wg people hated bee they felt that was sayg that beg gay is like beg black, that was -born, that would somehow ‘exce’ gay people or give them more rights, ” says Hamer. “On the other hand, gay people hated too bee, at that time, there were fears that the disvery would be mised to abort gay babi and wipe gay people off the face of the Earth.

IS A PERSON ‘BORN GAY’, OR IS BEG GAY A LEARNED BEHAVR?

”More like thisAlthough the fears rema, recent years the search for ‘gay gen’ has bee more accepted by the gay muny, no small part bee a blogil explanatn would unrme arguments that beg gay is a social or liftyle choice. The fact that intil tws have the same DNA and aternal tws share 50 per cent suggts that male homosexualy is gay geneIt was sctisg fay tre to see how homosexualy is hered that led Hamer to the disvery of Xq28. Now chief of the gene stcture and regulatn sectn at the US Natnal Cancer Instute, his study revealed a cur pattern: gay men tend to have more gay uncl and gay male s on their mother’s si of the fay than on their father’s.

THE 'GAY GENE' IS A MYTH BUT BEG GAY IS 'NATURAL,' SAY SCIENTISTS

This is bee mal her their X chromosome om their track down the DNA regn lked to the gay tra, Hamer ed a technique lled ‘lkage mappg’, an approach that lets geicists fd a gene even when they don’t know what do or where ’s loted. A subsequent study 1999 failed to replite Hamer’s rults and other rearchers are sceptil that Xq28 is lked to homosexualy at brothers, immune mothersMany scientists believe that exposure to hormon durg pregnancy heavily fluenc sexualy. Durg pre-natal velopment, for example, the sex ans a foet n regnise ttosterone, which will swch on gen to make om a few superficial differenc (among them penis and rg-fger length – both longer homosexuals), gay and straight men’s bodi appear the same.

The exceptn is homosexual men’s bras, which show remarkable siari to the bras of heterosexual women, suggtg that sexual orientatn pends on the effect hormon have on the velopg the two factors only go so far explag how homosexualy velops. Not only did he replite Blanchard’s birth orr effect, he also tected herance of homosexualy on the mother’s si, supportg Hamer’s ia of a gay gene on chromosome X. After Camper Ciani scribed the observed patterns pedigre of homosexualy – the effects of maternal herance and birth orr – his dghter suggted that he re-check his data to see if the female relativ of gay men had more children on the mother’s si.

THE LIFE OF THE GAY GENE: OM HYPOTHETIL GEIC MARKER TO SOCIAL REALY

Nippl are another example of a sexually antagonistic tra: they’re need for feedg babi, but velopg nippl men is a waste of the body’s rourc and allow errors leadg to breast search for sexualyEven if Camper Ciani’s fecundy factors are the same as Hamer’s gay gen, don’t tell what the specific gen actually do. Hamer speculat the gen might boost the size or nnectns om parts of the bra ed reproductn – such as the hypothalam – to make people more Sanrs’s study at NorthShore Universy uld fally reveal the inty and functn of ‘gay gen’.

“People we talked to at gay pri ftivals have signer-baby kd of worri – a geic tt employed a pre-natal way, or for employment and surance discrimatn, maybe the ary too. How Olr Brothers Influence HomosexualyHomosexualy might be partly driven by a mother’s immune rponse to her male fet—which creas wh each son she MacGregor / RtersHere’s what we know: Homosexualy is normal.

Female Japane maqu will even pete tersexually wh mal for exclive accs to female sexual ’s what we don’t know: What, specifilly, someone to bee gay, straight, or somethg between.

WHAT DO THE NEW ‘GAY GEN’ TELL ABOUT SEXUAL ORIENTATN?

Part of the explanatn is geic, but bee most intil tws of gay people are straight, heredy don’t expla “why” qutn is important bee “there is a strong rrelatn between beliefs about the origs of sexual orientatn and tolerance of non-heterosexualy, ” acrdg to the report thors, who are om seven universi spanng the globe.

THERE’S NO ONE ‘GAY GENE,’ BUT GEICS ARE LKED TO SAME-SEX BEHAVR, NEW STUDY SAYS

(When Atlantic ntributor Chandler Burr proposed his 1996 book, A Separate Creatn, that people are born gay, Southern Baptists lled to boytt Disney films and parks prott agast the publisher, Disney subsidiary Hypern. ) It shouldn’t matter whether people “choose” to be gay, but polilly, do—at least for of the most nsistent environmental explanatns for homosexualy is lled the “aternal birth orr effect. Average prevalence 2013 (Sav-Williams and Vrangalova)Acrdg to the report, Blanchard now plans to tt mothers of gay and straight men for the prence of the antibodi.

But gaps will rema, such as why some firstborn sons are gay, why some intil tws of gay sons are straight, and why women are gay, to name jt a review-paper thors do le out one explanatn for homosexualy, however: That tolerance for gay people enurag more people to bee gay. “Homosexual orientatn do not crease equency wh social tolerance, although s exprsn ( behavr and open intifitn) may do so, ” they reasong—that a tolerant society somehow enurag homosexualy to flourish—has been ed to support anti-gay legislatn Uganda, Rsia, and elsewhere.

In 1993, a study published the journal Science showed that fai wh two homosexual brothers were very likely to have certa geic markers on a regn of the X chromosome known as Xq28. In 1991, a study published the journal Science seemed to show that the hypothalam, which ntrols the release of sex hormon om the puary gland, gay men differs om the hypothalam straight men. PET and MRI studi performed 2008 have shown that the two halv of the bra are more symmetril homosexual men and heterosexual women than heterosexual men and homosexual women.