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

Contents:

• WE MAY KNOW WHY YOUNGER BROTHERS ARE MORE LIKELY TO BE GAY
• ARE YOUNGER BROTHERS MORE LIKELY TO BE GAY?
• MEN WH OLR BROTHERS ARE MORE LIKELY TO BE GAY, STUDY SUGGTS
• BOYS WH OLR BROTHERS MORE LIKELY TO BE GAY, STUDY SAYS

WE MAY KNOW WHY YOUNGER BROTHERS ARE 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.

Read more: What do the new gay gen tell about sexual orientatn? In 1996, the psychologists Ray Blanchard and Anthony Bogaert published a paper ntendg that homosexualy was more mon men who had olr brothers. "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.

ARE YOUNGER BROTHERS MORE LIKELY TO BE GAY?

"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). The rearchers examed data om 116 homosexual men and 62 heterosexual men om wtern and central Java.

Consistent wh Blanchard and Bogaert's fdgs Wtern societi, they found that homosexual men were more likely to have olr brothers than heterosexual men. To be specific, homosexual men their sample had an average of 0. 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.

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

The rearchers then tted whether homosexualy was visible the facial featur of Indonians. 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.

They did not, however, fd that homosexual men were any more femized their facial featur than heterosexual men. 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.

Homosexualy has been a long-standg pot of nfn for evolutnary psychologists. Male Homosexual Preference: Femy and the Olr Brother Effect Indonia. Men wh olr brothers are more likely to be gay, acrdg to a study published Wednday the journal Proceedgs of the Royal Society B.

BOYS WH OLR BROTHERS MORE LIKELY TO BE GAY, STUDY SAYS

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.

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.