Got an older brother? He may be the reason you're gay.

[Moondance]

CNN, December 12, 2017 ... If you're a guy with an older brother, there's an increased chance you're gay.

 

Scientists have noticed this pattern in previous research, but now they think they have a biological explanation as to why, and it starts long before birth. The results were published in the journal PNAS on Monday.

 

The researchers say that if their findings can be replicated, we may know at least one of the biological reasons some men are gay.

 

Many factors may determine someone's sexual orientation, but in this case, researchers noticed a pattern that may be linked to something that happens in the womb. The phenomenon is related to a protein linked to the Y chromosome (which women do not have) that is important to male brain development.

Researchers think it's possible that when a woman gets pregnant with her first boy, this Y-linked protein gets into her bloodstream. The mother's body recognizes the protein as a foreign substance, and her immune system responds, creating antibodies. If enough of these antibodies build up in the woman's body and she gets pregnant with another a boy, they can cross the placental barrier and enter the brain of the second male fetus.

 

"That may alter the functions in the brain, changing the direction of how the male fetus may later develop their sense of attraction," said study author Anthony Bogaert, a Canadian psychologist and professor in the departments of psychology and community health sciences at Brock University.

 

Earlier research has shown that the more older brothers a boy has, the more of a chance that boy will be attracted to men. A 2006 study showed that with each brother, the chance that a man will be gay goes up by about a third, but the researchers didn't determine why that was.

 

Bogaert and his co-authors tested a small group of 142 women and 12 men ages 18 to 80 and found a higher concentration of antibodies to the protein, known as NLGN4Y, in blood samples from women than from men. They found the highest concentration of antibodies to the protein in women with gay younger sons who had older brothers, compared with women who had no sons or who had given birth to only heterosexual boys.

 

The study builds on research Bogaert and his co-authors have been exploring for more than 20 years. Since their initial research that noted the trend, other research -- although not all studies -- have detected the phenomenon, even across cultures. One found that a man's chances of being gay increased even if he was raised apart from his older brother.

 

Researchers did not see a similar pattern in families with adopted brothers, so scientists started to think there must be a maternal developmental explanation. The research does not give a biological explanation for why some men may be bisexual or may not be attracted to anyone at all, nor can it give a biological explanation for gay only children, gay oldest sons or women who are attracted to women.

 

J. Michael Bailey, a professor in the Department of Psychology at Northwestern University, thinks the latest research is important. "It is significant, and I believe science granting agencies should put a high priority into additional research to see if this is true," he said.

 

Bailey was not involved in the new study but has worked on studies that have found genetic factors that may explain some differences in sexual orientations.

 

Bailey's latest paper, published this month in the journal Nature Research, looked at people's genomes and found several regions with single-letter DNA changes that were more common among gay men than straight men and may be relevant to the development of sexual orientation. Bailey believes this new study may be even more significant than general genetic findings if the findings can be replicated.

 

"Our studies only show that there may be genes that matter in sexual orientation," he said. "It is not like this study, that shows there is a potential specific mechanism by which sexual orientation may have changed prenatally. This is important work and fascinating if it proves to be true."

[mike carey]

I'm the eldest of three. I'm gay, my sister (2) is gay, and my brother (3) was straight as.

[LoveNDino]

I'm the eldest of three. I'm gay, my sister (2) is gay, and my brother (3) was straight as.

I am the eldest of 3 as well...Both my brother and sister are SAF...

[+ bigjoey]

I am the oldest of three. The others are straight.

[gallahadesquire]

Two older sisters. Well, it does say the odds increase.

[+ José Soplanucas]

I’m the eldest of four and the only one who is queer.

Edited December 12, 2017 by latbear4blk

[mike carey]

Ah, but in the tradition of Shakespeare's Macduff, I was not 'of woman born' so I suspect that makes a difference.

[Larstrup]

I’m the eldest of four and the onky one who is queer.

 

onky and queer. interesting.

[MikeyGMin]

It's interesting research. I remember hearing about it many years ago and I'm glad to know they have continued to study it. They have always been clear that they believe it is only one of the many possible prenatal or genetic predispositions for being gay.

 

It's true for me. Youngest of three boys and the only gay one. I also have a friend who comes from a very large family. Ten children altogether with six boys. He is the 5th boy and his younger brother is also gay.

[+ Charlie]

Well, the theory doesn't explain my spouse and his three brothers. The two older brothers are gay, the two younger brothers are straight.

[+ poolboy48220]

2nd of four, the only boy. I'm gay and the youngest sister is gay.

[EastbayMike]

I thought it was because I had an absent father and an overbearing mother.

[EastbayMike]

PS. I'm the middle child, one older brother and one younger sister. Both boys are gay and the girl is straight.

[amused1]

I'm the 2nd son. I'll have to thank my brother when I see him for Christmas.

[+ Gar1eth]

My younger brother is gay, so this is an interesting observation. I also find it interesting that second born children are nearly always taller than the first born child, regardless of gender.

 

 

I’m the third child and second born son. The force must have been strong with my brother as I believe the previous research has said that the more older brothers you have the more likely subsequent brothers are to be gay. I only have one brother. So he must have really stimulated whatever is supposed to go on in the Mothers. However my father was the second of two boys, and he wasn’t gay-as far as I know. He even liked looking at Playboys. One time when I was away at school, he ordered them in my name, so the Postman and others wouldn’t know they were for him.

 

Also I have some double 1st cousins. Two boys are in that family. My younger cousin, the second boy is straight also.

 

I’m sure it can’t be all this simple. Lots of things probably impact whether or not you are gay. To paraphrase the motto at the top of the Horoscope Page in my hometown newspaper growing up, “Having older brothers may impel but does not compel being gay!!”

 

Gman

[+ José Soplanucas]

I am always annoyed at all these studies searching for an explanation for homosexuality. You need an explanation only for the abnormal. Why do they not look for a cause for heterosexuality?

[+ Funguy]

What do we say about identical twins - one gay, one straight? Who came out first was the luck of the draw.

[+ stevenkesslar]

CNN, December 12, 2017 ... If you're a guy with an older brother, there's an increased chance you're gay.

 

I have 4 older brothers.

 

How Gay is that? :confused:

[+ stevenkesslar]

Why do they not look for a cause for heterosexuality?

 

I think because everybody's afraid of what we might find.

 

http://www.theblaze.com/wp-content/uploads/2017/10/harvey-weinstein-bill-clinton-1280x720.jpeg

[Moondance]

I have 4 older brothers.

 

How Gay is that? :confused:

So gay you could make a business out of it?

[+ sf westcoaster]

Two in the family, both of us are gay.

[+ Gar1eth]

I am always annoyed at all these studies searching for an explanation for homosexuality. You need an explanation only for the abnormal. Why do they not look for a cause for heterosexuality?

 

Because if it weren’t for heterosexuality, we wouldn’t have survived as a species.

 

Gman

[+ José Soplanucas]

Because if it weren’t for heterosexuality, we wouldn’t have survived as a species.

 

Gman

 

Well, such a key skill for survival should be better researched.

Ans besides, how do you know we would have survived as a species without homosexuality?

[+ Gar1eth]

I am always annoyed at all these studies searching for an explanation for homosexuality. You need an explanation only for the abnormal. Why do they not look for a cause for heterosexuality?

 

Because if it weren’t for heterosexuality, we wouldn’t have survived as a species.

 

Gman

 

Well, such a key skill for survival should be better researched.

Ans besides, how do you know we would have survived as a species without homosexuality?

 

Well even for the survival of our species, I’m not putting my tallywacker in there. I hope you can.

 

Gman

[MikeyGMin]

I am always annoyed at all these studies searching for an explanation for homosexuality. You need an explanation only for the abnormal. Why do they not look for a cause for heterosexuality?

Understanding the (likely multiple) reasons why people are born gay could be very beneficial. There are many people, including members of my own family, who still believe it is a choice. It would be very useful to understand the biological reasons why homosexuality is a natural variation. It's not going to matter to the true bigots of the world, but it could help with some of the more reasonable types.