The More Older Brothers You Have, The More Likely You Are To Be Gay. Now We Might Finally Know Why

research worker believe that increasing levels of certain antibody in a mother could explain the occurrence of the “ fraternal birth order effect ” , where   the more older brothers a male has , the more likely he is to be gay .

The research , published in theProceedings of the National Academy of Sciences , looked for a biological factor in mother that could roll up over multiple manly pregnancies and charm their offspring ’s sexual predilection .

The squad , lead by Anthony Bogaert from Brock University , found that women pregnant with boys develop antibodies that target protein NLGN4Y , which is produce by the Y chromosome . It ’s not uncommon for women to bring about immune responses to molecules produced by the foetus , it happens if female parent and babe have different bloodline groups , but the particular reaction to NLGN4Y offend the researchers ' interest . The protein plays a office in how brainiac networks uprise .

The researchers assume that this protein work the regions of the brain where attraction is moderated   and that exposure to higher anti - NLGN4Y stage   makes same - sex attractor more likely .

They analyzed the blood of 142 women and found that those with brave sons with older brothers had ,   indeed , higher levels of NLGN4Y antibodies than mothers of jocund sons with no older brother . Women with straight son , no sons , and also world had progressively lower levels of these antibodies .

“ I would n’t say we ’ve solved the fraternal giving birth order core mystifier , but we are vex close to find a mechanism , ” Bogaert toldNew Scientist .

It ’s important to note that the research only involved a   small phone number of adult female , so it ’s not potential to close whether this is the true biological mechanism behind the brotherly birth order effect . It is also necessary to be cognizant that said effect is estimated to play a role in the intimate preference of only15 percentof merry man .

Even if levels of NLGN4Y   are involved in determining sexuality , this can only be a small part of the teaser . Many written report face at the biological factors behind gayness blank out about charwoman , as well as epicene and pansexual people . If the conundrum has to be solved , a more astray - arrive at approach is probably necessary .

[ H / T : New Scientist ]