Largt study of gay brothers hom on 'gay gen' | New Scientist

Contents:

• LARGT STUDY OF GAY BROTHERS HOM ON 'GAY GEN'
• A GAY COUPLE'S FIGHT FOR THEIR TW SON'S CIZENSHIP INSPIR
• SCIENTISTS FD DNA DIFFERENC BETWEEN GAY MEN AND THEIR STRAIGHT TW BROTHERS
• NO ‘GAY GENE’: MASSIVE STUDY HOM ON GEIC BASIS OF HUMAN SEXUALY
• 'GAY GEN': SCIENCE IS ON THE RIGHT TRACK, WE'RE BORN THIS WAY. LET’S AL WH .
• SOME RANDOM THOUGHTS ON ‘GAY GENE’ STUDI

LARGT STUDY OF GAY BROTHERS HOM ON 'GAY GEN'

Tw pairs which at least one tw is homosexual were soliced through announcements the gay prs and personal referrals om 1980 to the prent. Two sets ntaed a pair of monozygotic tws nrdant for sexual orientatn wh the third triplet dizygotic and disrdant for homosexual orientatn. In a study where scientists looked at the sexual aroal patterns of intil tws wh different sexuali—specifilly, where one was gay and the other was straight—they found that gay tws monstrated more genal aroal rponse to same-sex imag, whereas straight tws monstrated more aroal rponse to oppose-sex imag [2].

In theory, this means two people uld rry “gay gen, ” but both of them wouldn’t necsarily be gay pendg on certa environmental factors.

Most of the more recent rearch on possible blogil origs of homosexualy has foced on the gree to which gen, along wh other prenatal factors such as hormon and epi-geics, may fluence the velopment of homosexualy. The former approach of recg intil tws via advertisements gay and lbian publitns is now known to have a very strong “volunteer effect” that produced the appearance of relatively large geic effects (1). Neverthels, even wh the e of large tw registri, the number of intil tw pairs found wh homosexualy is often very small dividual studi, rultg a standard viatn that is greater than the lculated geic effect, meang that the rults are not statistilly different om zero.

A GAY COUPLE'S FIGHT FOR THEIR TW SON'S CIZENSHIP INSPIR

Whehead and Whehead (1) have prented and discsed, some tail, the and other problems herent tw studi of homosexualy and have prented reasons to expect that the geic fluence on, or ntributn to, homosexualy will eventually be agreed to be the 10%-15% range (i. Another reason has to do wh the apparently predomant fluence of post-natal environmental factors on the velopment of homosexualy (10). Schumm (9) found that children wh homosexual parents are 12-15 tim more likely than children of heterosexual parents to be homosexual as adults.

SCIENTISTS FD DNA DIFFERENC BETWEEN GAY MEN AND THEIR STRAIGHT TW BROTHERS

This is the strongt environmental fluence ever reported for the velopment of homosexualy, and volv very close fay members, the parent-child relatnship. The rults of a study by Kg and McDonald (8) illtrate how such a close, fay relatnship uld flate the lculated geic fluence on homosexualy  intil tw studi.

They studied 46 tw pairs havg homosexualy prent one or both of the tws each pair and found that 54% of the tw pairs had discsed their sexual orientatn wh each other, 89% had “shared knowledge” of each other’s sexual orientatn, and 30% of the tw pairs had actually had sex wh each other. Bee intil tws intify so closely wh each other, and post-natal experienc – pecially close fay relatnships – strongly affect the velopment of homosexualy, seems plsible, if not likely, that a homosexual member of a tw pair would fluence the other member of that pair to embrace and explore homosexualy also, th flatg the apparent geic fluence reported intil tw studi.

That is to say, a signifint portn of what may appear, intil tw studi, to be a geic fluence on the velopment of homosexualy may turn out to be, stead, a post-natal, environmental fluence volvg shared knowledge of sexual orientatn and shared sexual experienc wh intil tw pairs.

NO ‘GAY GENE’: MASSIVE STUDY HOM ON GEIC BASIS OF HUMAN SEXUALY

The “pair-wise nrdance” answers the simple qutn, “Where one tw of an intil pair is homosexual, what percentage of -tws is also homosexual”. This rult would dite that for every tw pair wh both members beg homosexual, there are 9 tw pairs wh only one homosexual member.

'GAY GEN': SCIENCE IS ON THE RIGHT TRACK, WE'RE BORN THIS WAY. LET’S AL WH .

The pair-wise nrdance valu dite that for every tw pair wh both members beg homosexual, there are 7 tw pairs wh only one homosexual member. Now, pare this rult to the range of theoretilly possible out where no tw pairs would both be homosexual (= 0%) and where all tw pairs would both be homosexual (= 100%) and you n see, tuively, that a pair-wise nrdance of only 13. Therefore, on the basis of pair-wise nrdance intil tws, seems appropriate to nclu that there is, at the most, only a mor geic ntributn to the velopment of homosexualy, and that this relatively mor fluence n be overe (i.

This timate of nrdance is necsary orr to e both intil and aternal tws a study to disentangle the relative ntributns to homosexualy of geic and non-geic (environmental) factors. The effect is to greatly crease, relative to pair-wise nrdance valu, the apparent geic ntributn to homosexualy intil tw studi. While pair-wise nrdance giv an tuive ditn of the geic fluence on homosexualy as exprsed intil tws, do not provi rmatn on what factors may provi the remag, non-geic fluence.

In a meta-analysis, Whehead (6), g the rults om seven of the recent tw registry studi that were signed to reveal ntributns of both geic and non-geic factors to homosexualy, found that the mean ntributn of geics to male homosexualy was around 22%, and to female homosexualy, around 33%. Such levels of geic ntributn dite a real but weak-to-weakly morate and termate role of geics the velopment of homosexualy. Furthermore, the non-shared, post-natal environmental ntributn to homosexualy is morate to strong, around 64%-78%, has a relatively small standard viatn and is nsistently around the same percentage (6), ditg that homosexualy is fluenced primarily by post-natal environmental factors and experienc that are not directly related to prenatal, blogil ntributns of any kd or batn.

SOME RANDOM THOUGHTS ON ‘GAY GENE’ STUDI

They ed a very large sample (9, 884) of tws om the Atralian Tw Registry, one of the largt sampl to date for tw studi of homosexualy.