Having Older Brothers Increases a Man's Odds of Being Gay

[Epikur]

Quote

Gay men have, on average, a greater number of older brothers than do heterosexual men, a well-known finding within sexual science. This finding has been termed the fraternal birth order effect. Strong scientific interest in sexual orientation exists because it is a fundamental human characteristic, and because its origins are often the focal point of considerable social controversy. Our study is a major advance in understanding the origins of sexual orientation in men by providing support for a theorized but previously unexamined biological mechanism—a maternal immune response to a protein important in male fetal brain development—and by beginning to explain one of the most reliable correlates of male homosexuality: older brothers.


 

ABSTRACT

We conducted a direct test of an immunological explanation of the finding that gay men have a greater number of older brothers than do heterosexual men. This explanation posits that some mothers develop antibodies against a Y-linked protein important in male brain development, and that this effect becomes increasingly likely with each male gestation, altering brain structures underlying sexual orientation in their later-born sons. Immune assays targeting two Y-linked proteins important in brain development—protocadherin 11 Y-linked (PCDH11Y) and neuroligin 4 Y-linked (NLGN4Y; isoforms 1 and 2)—were developed. Plasma from mothers of sons, about half of whom had a gay son, along with additional controls (women with no sons, men) was analyzed for male protein-specific antibodies.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5777026/#r12

Edited November 3, 2021 by Epikur

[Preety_India]

I have observed this where I saw a guy around a bunch of women for a few years (with not much male contact) and he was beginning to act girlish. I guess effect of company. 

 

[Epikur]

6 minutes ago, Preety_India said:

I have observed this where I saw a guy around a bunch of women for a few years (with not much male contact) and he was beginning to act girlish. I guess effect of company. 

 

I guess you did not read the text properly. It deals with something different.

[Preety_India]

1 minute ago, Epikur said:

I guess you did not read the text properly. It deals with something different.

Was just giving you an example of a similar but opposite phenomenon. 

 

[Epikur]

Just now, Preety_India said:

Was just giving you an example of a similar but opposite phenomenon. 

 

Ok

[Rilles]

That makes sense. I have 4 brothers and one of them is openly gay. 

Edited November 3, 2021 by Rilles

[Epikur]

There might be some correlation to this:
 

Quote

In the Samoan islands, androphilic males are referred to as fa'afafine. Translated literally, fa'afafine means ‘in the manner of a woman’. Indeed, a small number of fa'afafine self-identify as women, even though they recognize, as do all Samoans, that they differ physically and socially from biological women. Most, however, self-identify as fa'afafine and not as men. Although the term fa'afafine implies that the members of this category are uniformly very feminine, they are, in fact, a heterogeneous group in many ways (Schmidt 2003; Bartlett & Vasey 2006). In appearance and mannerisms, although most would be considered effeminate, they range from strikingly feminine to unremarkably masculine.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2176197/

[Bojan V]

I am an older brother, and i am gay!

How typical to "study" us, gay people! It's a subtle homophobia.

They never "study" heteros in the same way. 

"If you have a younger sister, it is more likely to be hetero." Nonsense! All of it.

[Epikur]

32 minutes ago, Bojan V said:

I am an older brother, and i am gay!

How typical to "study" us, gay people! It's a subtle homophobia.

They never "study" heteros in the same way. 

"If you have a younger sister, it is more likely to be hetero." Nonsense! All of it.

Well that disproves it obviously. Thanks for the input.

 

[Epikur]

1 hour ago, Knowledge Hoarder said:

Another scientific vomit of a study.

Science denial is big in this thread. 

Quote

Fraternal birth order has been correlated with male sexual orientation, with a significant volume of research finding that the more older brothers a male has from the same mother, the greater the probability he will have a homosexual orientation. Ray Blanchard and Anthony Bogaert first identified the association in the 1990s and named it the fraternal birth order effect. Scientists have attributed the effect to a prenatal biological mechanism, since the association is only present in men with older biological brothers, and not present among men with older step-brothers and adoptive brothers. The mechanism is thought to be a maternal immune response to male fetuses, whereby antibodies neutralize male Y-proteins thought to play a role in sexual differentiation during development. This would leave some regions of the brain associated with sexual orientation in the 'female typical' arrangement – or attracted to men. Biochemical evidence for this hypothesis was identified in 2017, finding mothers with a gay son, particularly those with older brothers, had heightened levels of antibodies to the NLGN4Y Y-protein than mothers with heterosexual sons.[1][2]

The effect becomes stronger with each additional male pregnancy, with odds of the next son being gay increasing by 38–48%. This does not mean that all or most sons will be gay after several male pregnancies, but rather, the odds of having a gay son increase from approximately 2% for the first born son, to 3% for the second, 5% for the third and so on.[1][3] Two studies have estimated between 15% and 29% of gay men owe their sexual orientation to this effect, but noted that the number may be higher since prior miscarriages and terminations may have exposed their mothers to Y-linked antigens. It has generally been thought that this maternal response would not apply to first born gay sons and that they may owe their orientation to genes, prenatal hormones and other maternal immune responses which also influence brain development.[2] However, the 2017 lab study found that mothers with no sons had antibodies to male cells, which may be caused by common early miscarriages, and thus induce the effect for a first live born son.[4] A variety of evolutionary explanations for why the response persists have been offered by scientists.[5]
 

https://en.wikipedia.org/wiki/Fraternal_birth_order_and_male_sexual_orientation


 

[Epikur]

6 minutes ago, Knowledge Hoarder said:

@Epikur They recognized a pattern, and identified possible causes. Fair enough.

I'm sure there are plenty of examples where this both applies and doesn't apply.

Welcome back to science

[kray]

Wtf........

[Carl-Richard]

How many older brothers do you have?  

[Rilles]

Can someone explain why people are offended at this? I dont get it. 

[Epikur]

23 minutes ago, Rilles said:

Can someone explain why people are offended at this? I dont get it. 

It could be a gateway to studies which could be more problematic I guess

[Rilles]

1 minute ago, Epikur said:

It could be a gateway to studies which could be more problematic I guess

Studying that homosexuality starts in the womb is a huge win though. Of course we should study homosexuality, we should study all sexualities. 

[Epikur]

23 minutes ago, Rilles said:

Studying that homosexuality starts in the womb is a huge win though. Of course we should study homosexuality, we should study all sexualities. 

I agree 

[Raptorsin7]

3 hours ago, Rilles said:

Can someone explain why people are offended at this? I dont get it. 

Because the op is questioning his sexuality and trying to understand homosexuality, but it's based on some root aversion.

And people who are already homosexual don't want to understand it further, because they have based their identity around it now. To question their homosexuality, would be to question their identity 

 

Edited November 4, 2021 by Raptorsin7

[Rilles]

7 minutes ago, Raptorsin7 said:

Because the op is questioning his sexuality and trying to understand homosexuality, but it's based on some root aversion.

 

Have their been other threads on this? Where did he say he was questioning it?

I dont ask of anyone to question their sexuality, that would be kind of dumb, you know your sexuality as soon as you see someone naked, either youre attracted or repelled or attracted to both sexes. What I am interested in though its settling the stupid "womb or choice" argument that conservatives make. That can be solved with science.

Edited November 4, 2021 by Rilles

[Raptorsin7]

8 minutes ago, Rilles said:

Have their been other threads on this? Where did he say he was questioning it?

I dont ask of anyone to question their sexuality, that would be kind of dumb, you know your sexuality as soon as you see someone naked, either youre attracted or repelled or attracted to both sexes. What I am interested in though its settling the stupid "womb or choice" argument that conservatives make. That can be solved with science.

That's just what I assumed from the thread, I could be wrong.

Are you certain in can be solved with science?