Why would people 'choose' to be gay? | Science | The Guardian

Contents:

• WHY ARE THERE GAY MEN?
• ‘I AM GAY – BUT I WASN’T BORN THIS WAY’
• ARE WE BORN GAY?
• WHAT SCIENCE KNOWS ABOUT WHY PEOPLE ARE GAY
• WHY WOULD PEOPLE 'CHOOSE' TO BE GAY?
• BORN TO BOTTOM? REARCHERS REPORT BLOGIL CORRELATNS ANAL SEX ROLE GAY MEN

WHY ARE THERE GAY MEN?

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.

(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.

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.

‘I AM GAY – BUT I WASN’T BORN THIS WAY’

“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. Scientists may have fally solved the puzzle of what mak a person gay, and how is passed om parents to their children.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 mother.The 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 lk.Long 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."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 not.Rice and his team created a mathematil mol that explas why homosexualy is passed through epi-marks, not geics.

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. Rice not that the markers are "highly variable" and that only strong epi-marks will rult a homosexual offsprg.Though 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."Most mastream blogists have shied away om studyg bee of the social stigma," he says. Well there are many exampl of homosexualy nature, 's very mon." Homosexual behavr has been observed black swans, pengus, sheep, and other animals, he says.Rice'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."We've found a story that looks really good," he says.

ARE WE BORN GAY?

Effectively, then, the mother's immune system would (sometim) treat certa male protes produced by the fet as a foreign pathogen and attempt to attack , rultg out that uld clu a homosexual orientatn, but also fetal loss if the reactn was strong enough (i. Already there is a lot to like about this hypothis on a theoretil level, as don't pos any hidn adaptive benefs for a homosexual orientatn (as such proposed benefs have not received sound empiril support historilly).

The mothers were then classified further to one of five groups: those wh gay male only-children (n = 8), those wh gay male offsprg that had no olr brothers (n = 23), those wh gay male offsprg wh olr brothers (n = 23), those wh heterosexual male only-children (n = 11), and those wh heterosexual male offsprg wh siblgs (n = 61).

WHAT SCIENCE KNOWS ABOUT WHY PEOPLE ARE GAY

As birth weight tends to crease over succsive pregnanci, the parisons were limed to first live-born sons only (n = 63); this left 4 gay male only-children, 7 gay mal wh no olr brothers, 14 heterosexual mal wh gay younger brothers, 10 heterosexual male only-children, and 28 heterosexual mal wh siblgs.

WHY WOULD PEOPLE 'CHOOSE' TO BE GAY?

While 's important to not get rried away wh this fdg given the relatively small sample size (I wouldn't put too much stock an N of 8), there is some suggtive evince here worth pursug further that somethg is atypil fetal velopment the se of gay male offsprg.

Skorska et al (2016) pos that this might have somethg to do wh some mothers showg a greater immune rponse agast male offsprg, rultg more fetal loss, the rult beg that such mothers are both ls likely to have any children at all and more likely to have gay male children particular. If mothers of gay men do not tend to have a greater rat of female-to-male offsprg, this would st some doubt on the explanatn (and, sce the only data I've heard reports that gay men tend to have more olr brothers, seems they would have noticed the sister pot by now if existed). On the other hand, if this is a more general immune reactn agast fetal bodi, regardls of their sex, we would not expect such a pattern ( might also predict that mothers takg immunosupprsants would be ls likely to have gay offsprg/misrry, but thgs are unlikely to be that simple owg to the fact that other effects would rult too).

BORN TO BOTTOM? REARCHERS REPORT BLOGIL CORRELATNS ANAL SEX ROLE GAY MEN

But nsirg that the tra disurag the type of sex that leads to procreatn — that is, sex wh women — and would therefore seem to thwart s own chanc of beg geilly passed on to the next generatn, why are there gay men at all? For several years, studi led by Andrea Camper Ciani at the Universy of Padova Italy and others have found that mothers and maternal nts of gay men tend to have signifintly more offsprg than the maternal relativ of straight men.

The rults show strong support for the "balancg selectn hypothis, " which is fast beg the accepted theory of the geic basis of male theory holds that the same geic factors that duce gayns mal also promote fecundy (high reproductive succs) those mal' female maternal relativ. Through this tra-off, the maternal relativ' "gay man gen, " though they aren't exprsed as such, tend to get passed to future generatns spe of their tenncy to make their male herors no one knows which gen, exactly, the might be, at least one of them appears to be loted on the X chromosome, acrdg to geic molg by Camper Ciani and his lleagu.

Mal her only one X chromosome — the one om their mother — and if clus the gene that promot gayns mal and fecundy femal, he is likely to be gay while his mom and her female relativ are likely to have lots of kids.