What Science Knows About Why People Are Gay

Contents:

• WHY ARE PEOPLE GAY? GAY BY CHOICE OR IS BEG GAY GEIC?
• SCIENTISTS MAY HAVE FALLY UNLOCKED PUZZLE OF WHY PEOPLE ARE GAY
• WHAT SOMEONE TO BE GAY OR STRAIGHT?
• WHAT SCIENCE KNOWS ABOUT WHY PEOPLE ARE GAY
• WHY ARE THERE GAY MEN?

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

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 has.Le MacGregor / RtersHere’s what we know: Homosexualy is normal. Between 2 and 11 percent of human adults report experiencg some homosexual feelgs, though the figure vari wily pendg on the survey.Homosexualy exists across cultur and even throughout the animal kgdom, as the thors of a mammoth new review paper on homosexualy wre.

Female Japane maqu will even pete tersexually wh mal for exclive accs to female sexual partners.Here’s what we don’t know: What, specifilly, someone to bee gay, straight, or somethg between. Part of the explanatn is geic, but bee most intil tws of gay people are straight, heredy don’t expla everythg.The “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.) It shouldn’t matter whether people “choose” to be gay, but polilly, do—at least for now.One of the most nsistent environmental explanatns for homosexualy is lled the “aternal birth orr effect.” Essentially, the more olr brothers a man has, the more likely he is to be gay.

Studi have found that a man whout olr brothers has about a 2 percent chance of beg gay, but one wh four olr brothers has a 6 percent chance.

SCIENTISTS MAY HAVE FALLY UNLOCKED PUZZLE OF WHY PEOPLE ARE GAY

(Meanwhile, other studi have found the relatnship to be weak or nonexistent.) As psychologist Rch Sav-Williams wr an acpanyg mentary, the oute for any given baby boy might pend on the timg of the immune rponse and the fet’s sceptibily to the antibodi.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.

If proved out, fetal birth orr uld do a lot to fill the missg explanatns for homosexualy. 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 few.The 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 wre.That reasong—that a tolerant society somehow enurag homosexualy to flourish—has been ed to support anti-gay legislatn Uganda, Rsia, and elsewhere. The laws do margalize and shame gay people, the thors wre.

Specifilly, many aspects of the velopment of homosexualy (both the male and female varieti) are not as well unrstood as they should be to make some of the claims that many people felt nfint exprsg. There's a lot to discs regardg the rults of the paper (Skorska et al, 2016): The rearchers were examg the possibily that a maternal immune rponse might play a key role the velopment of a homosexual orientatn mal.

WHAT SOMEONE TO BE GAY OR STRAIGHT?

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.e., a misrriage). 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 rearchers reced approximately 130 mothers and classified them on the basis of what kd of children they had: those who had at least 1 gay son (n = 54), and those who only had heterosexual sons (n = 72). 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).

As predicted, the average number of fetal loss were higher the first group (mothers of gay male only-children; M = 1.25), relative to all the other groups (d = 0.76), which did not signifintly differ om each other (rpective Ms = 0.43, 0.74, 0.09, and 0.39). When nsired terms of the rat of misrriag to live to births, a siar picture emerged: mothers of gay male only-children reported more misrriag to live births (M = 1.25) than the other groups (d = 1.55), which did not differ om each other (rpective Ms = 0.14, 0.24, 0.09, and 0.17). 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.

WHAT SCIENCE KNOWS ABOUT WHY PEOPLE ARE GAY

The rults mirrored those of the fetal-loss data: mothers of gay male only-children tend to give birth to fants that weighed signifintly ls (M = 2970 grams), than all other groups (d = 1.21), which did not differ (rpective Ms = 3713, 3489, 3506, and 3633). In sum, then, mothers of gay male only-children tend to have a greater number of misrriag and give birth to signifintly lighter offsprg than mothers of other kds.

WHY ARE THERE GAY MEN?

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.

The first qutn that to md is why this effect seemed to be specific to gay male only-children, rather than gay male children wh siblgs? 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.