By RANDOLPH E. SCHMID, Associated Press Writer




WASHINGTON - Having several older brothers increases the likelihood of a man being gay, a finding researchers say adds weight to the idea that there is a biological basis for sexual orientation.


"It's likely to be a prenatal effect," said Anthony F. Bogaert of Brock University in St. Catharines, Canada, "This and other studies suggest that there is probably a biological basis for" homosexuality.

S. Marc Breedlove of Michigan State University said the finding "absolutely" confirms a physical basis.

"Anybody's first guess would have been that the older brothers were having an effect socially, but this data doesn't support that," Breedlove said in a telephone interview.

The only link between the brothers is the mother and so the effect has to be through the mother, especially since stepbrothers didn't have the effect, said Breedlove, who was not part of the research.

Bogaert studied four groups of Canadian men, a total of 944 people, analyzing the number of brothers and sisters each had, whether or not they lived with those siblings and whether the siblings were related by blood or adopted.

He reports in a paper appearing in Tuesday's issue of Proceedings of the National Academy of Sciences that having several biological older brothers increased the chance of a man being gay.

It's an effect that can be detected with one older brother and becomes stronger with three or four or more, Bogaert said in a telephone interview.

But, he added, this needs to be looked at in context of the overall rate of homosexuality in men, which he suggested is about 3 percent. With several older brothers the rate may increase from 3 percent to 5 percent, he said, but that still means 95 percent of men with several older brothers are heterosexual.

The effect of birth order on male homosexuality has been reported previously but Bogaert's work is the first designed to rule out social or environmental effects.

Bogaert said he concluded the effect was biological by comparing men with biological brothers to those with brothers to whom they were not biologically related.

The increase in the likelihood of being gay was seen only in those whose brothers had the same mothers, whether they were raised together or not, he said.

Men raised with several older step- or adopted brothers do not have an increased chance of being gay.

"So what that means is that the environment a person is raised in really makes not much difference," he said.

What makes a difference, he said, is having older brothers who shared the same womb and gestational experience, suggesting the difference is because of "some sort of prenatal factor."

One possibility, he suggests, is a maternal immune response to succeeding male fetuses. The mother may react to a male fetus as foreign but not to a female fetus because the mother is also female.

It might be like the maternal immune response that can occur when a mother has Rh-negative blood but her fetus has Rh-positive blood. Without treatment, the mother can develop antibodies that may attack the fetus during future pregnancies.

Whether that's what is happening remains to be seen, but it is a provocative hypothesis, said a commentary by Breedlove, David A. Puts and Cynthia L. Jordan, all of Michigan State.

The research was funded by the Social Sciences and Humanities Research Council of Canada

yes, Provacative is right.

and i thought i was an only child all this time!!!

Anx said:

i read about this some years ago. never knew what to think of it. i always thought what about parents with one child who is gay or parents whose oldest brother or sister is gay? i dunno. the article confuses me. i just assumed that being gay is like any other genetic make up of a person, like brown eyes or red hair....etc.

Yet another in my "could be gay" checklist.

It doesn't surprise me...statistic wise. Eventually a gay has to pop out But seriously, they're going to find out being gay is in the genes. It's prevelent in twins and also it's not uncommon to see it skip across generations like the "gay uncle" factor.

superspaceboy said:

i read somewhere that people with scary prince avatars are likely to be gay!

kidelrich said:

Anx said:

Wonder where I got "said scary prince avie"
[Edited 6/26/06 11:02am]

Last month, when this same BS thread was posted, the results were overwellmingly against the findings.

MickG said:

I don't think it's entirely BS. The fact that they are starting to relate homosexuality to genetics is a good thing.

For the gay guys here, how many of you believe you were born gay? I'm being serious, I've always wondered if the majority of gay people believe that is genetic and not social.

jerseykrs said:

It's COMPLETELY genetic. There is nothing social about it. I was born into an ultra religious, heterosexual family. I am the only gay one.

...besides this is some B.S. I'm the oldest out of 3 kids and I'm gay as hell and my brother is the straightest motherfucker in the GALAXY. It's weird. There's a constant clash between us. We subliminally bring up our sexualities in conversation just to annoy each other.

jerseykrs said:

I believe I was born gay. Of course there WERE circumstances that I believe contributed and helped me realize I was gay. But I firmly believe both of my parents were bi in some way or another. I believe many people are gay or bi it's just that their environment in general plays a big factor in how much one recognizes and thusly explores their sexuality.

superspaceboy said:

Where is Cynthia at? He's the senior ghey on here.

superspaceboy said:

Thank you, I've always wondered if that is like a hotly debatable topic with homosexuals. I would think enviorment has some kind of effect on how one pursues their obvious difficult feelings at an early age.

jerseykrs said:

I don't believe I was born gay, I know I was born that way, as far back as I can remember I knew I was different to most of the other boys at school even though I didn't understand what it was. It was only as I got older that I realised what it was and it scared the fucking shit out of me.

I feel quite comfortable with it now but I spent years trying to deny it.

xenon said:

That was quite an honest post, thank you. What scared you the most?

jerseykrs said:

You know what scared me? I really really really really thought I was going to hell. I NEVER had a crush on a guy before and the first time I did it scared the shit out of me. I would stay up for hours past my bed time praying to be "cured". I did that for 7 years and nothing changed. So I figured this is the way God wanted me and I started praying for self love and acceptance.

jerseykrs said:

Not sure where to start or even if I want to (still got a few little hang ups about it), but the thing I was probably most scared about was being rejected by my family and friends.

it's not totally genetic. it's not totally conditioned. it depends on the person. anyone who believes it's 1,000% one or the other might as well believe in leeches and bloodletting.

not that there's anything wrong with that, i guess.

Anx said:

It's completely genetic for me. There was nothing else growing up that could've influenced it. It was just like a switch went off. One day I was chasing girls on the playground, the next I was thinking about ass and Judy Garland.

DiscoballStallion said:

Does this mean I can't be gay since I hate Judy Garland, showtunes and house music? I mean, I have an older brother for cryin' out loud.

kidelrich said:

DiscoballStallion said:

That's exactly how I felt growing up.

kidelrich said:

Does that mean I can't be gay
I hate hate hate hate HATE HATE HATE HATE Showtunes. ANYONE singing them around me will receive a quick and prompt fist to the mouth. I hate ALL things theatre. Theatre gays are THE single most ANNOYING type of gay. I'd rather deal with feminine psycho diso raver twinks than Theatre Gays.

Anx said:

How does that work then?

In all seriousness though do you remember when you first realised?

kidelrich said:

You best be passing that gay card over here for some punches is all.

kidelrich said:

i'm not a fan of these things either, yet i am the gay. could it be because i have no older brother and my gay gene isn't complete?