We may know why younger brothers are more likely to be gay | New Scientist

Contents:

• MEN WH OLR BROTHERS ARE MORE LIKELY TO BE GAY, STUDY SUGGTS
• IS A PERSON ‘BORN GAY’, OR IS BEG GAY A LEARNED BEHAVR?
• WE MAY KNOW WHY YOUNGER BROTHERS ARE MORE LIKELY TO BE GAY
• ARE YOUNGER BROTHERS MORE LIKELY TO BE GAY?
• GAY GEICS
• NEWS & TECHNOLOGYTHE BLOGY OF BEG GAY
• THE LAMBDA: ALL THGS GAY & FRATERNAL
• YOU’RE NOT BREAKG BARRIERS BY BEG GAY A ATERNY
• GAY HISTORY OF MEN’S FRATERNI
• GENR NONNFORMY AND BIRTH ORR RELATN TO ANAL SEX ROLE AMONG GAY MEN

MEN WH OLR BROTHERS ARE MORE LIKELY TO BE GAY, STUDY SUGGTS

Men wh olr brothers are more likely to be gay, acrdg to a study published Wednday the journal Proceedgs of the Royal Society B. This new report builds upon prev rearch regardg male birth orr and homosexualy, though there is still no cisive ncln as to why there’s a lk between the cross-analyzg data om 10 scientific studi wh more than 5, 000 subjects, rearchers found that men wh olr brothers were 38 percent more likely to intify as gay. ”The study, which pared the probabily of the youngt brother a two-son fay beg gay as pared to the olst son, did not clu female subjects, as prev rearch has tablished that women do not fluence the sexual orientatn of their younger siblgs, acrdg to this study did not terme a ncrete reason for the rrelatn between a man havg an olr brother and intifyg as gay, Blanchard said that “pots toward the need for more rearch on the 'maternal immune hypothis'” — a theory Blanchard troduced 1996 that suggts that a mother is exposed to “male-specific substanc” durg pregnancy wh or the birth of a son.

Acrdg to proponents of the theory, the mother’s immune rponse is changed durg the pregnancy of a boy, creasg the likelihood that a subsequent male child would be gay.

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

If the DNA sequence were the only thg termg whether someone is gay or not, we would expect intil tws to match 100% of the time.

WE MAY KNOW WHY YOUNGER BROTHERS ARE MORE LIKELY TO BE GAY

Of urse, this isn’t the only environmental explanatn for how people are born gay – there are plenty of men wh olr brothers who are not gay.

This uld mean that there are some gen that are passed down om the mother’s si that make women more fertile and make men more likely to be gay. No matter why those gen are still around, we do know that beg gay is partly geic and partly termed before a baby is even born.

ARE YOUNGER BROTHERS MORE LIKELY TO BE GAY?

The more olr brothers a boy has, the more likely he is to be gay when he grows up – an effect lled the “aternal birth orr effect”. They found that the mothers of gay sons wh olr brothers had the hight levels of antibodi agast this prote, followed by the mothers of gay sons wh no olr brothers.

“Given that the prote is known to be important synapse formatn, you n see how maternal antibodi might affect the wirg of the fetal bra, and that might expla why each subsequent son is more likely to grow up gay. “The signifince of this prelimary observatn, if n be replited, is that intifi specific molecul the bra that may be important for heterosexual as well as homosexual velopment, ” says Dean Hamer, a pneer of rearchg the blogil termants of sexual orientatn.

GAY GEICS

In 1996, the psychologists Ray Blanchard and Anthony Bogaert published a paper ntendg that homosexualy was more mon men who had olr brothers.

NEWS & TECHNOLOGYTHE BLOGY OF BEG GAY

"In [Wtern] societi, homosexual men are femized at var levels and they have more olr brothers than heterosexual men, " state the thors of the study. "To evaluate whether femy and the aternal birth orr effect are universal featur of male homosexual preference or not, we llected origal data om homosexual men, heterosexual men, and heterosexual women om Java (Indonia).

Consistent wh Blanchard and Bogaert's fdgs Wtern societi, they found that homosexual men were more likely to have olr brothers than heterosexual men.

THE LAMBDA: ALL THGS GAY & FRATERNAL

Intertgly, the rearchers also found that homosexual men were more likely to have olr sisters, although this difference was smaller than the olr brother difference. Usg standardized photographs of heterosexual and homosexual Indonian men, the rearchers found that men wh olr brothers were perceived to have more feme facial featur than men whout olr brothers.

YOU’RE NOT BREAKG BARRIERS BY BEG GAY A ATERNY

The thors wre, "Taken together, the rults suggt the prence of a femizg factor associated wh male homosexualy that is partially termed by male birth orr. 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. It’s held aloft by Dr Alan Sanrs and a group of lleagu om NorthShore Universy near Chigo who are attendg a gay pri ftival.

GAY HISTORY OF MEN’S FRATERNI

“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.

”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. For stance, intil tw brothers (siblgs rived om the same fertilised egg) are more likely to both be gay than aternal tws (tws that velop om separate eggs).

GENR NONNFORMY AND BIRTH ORR RELATN TO ANAL SEX ROLE AMONG GAY MEN

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.

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. Lkage mappg works bee close relativ like brothers share not only a particular tra, such as homosexualy, but also the gen unrlyg the tra.