Causes to Homosexual Behaviour

[Menydh]

Homosexuality Again Linked to Biological Factors

'Fraternal birth order' predicted men's sexual orientation, research shows.

HealthDay
June 26, 2006

Adding to the theory that homosexuality may be hardwired and not the product of environmental factors, new research again confirms that the more older brothers a male has, the more likely he is to be gay.

Researchers have known for years that a man's likelihood of being gay rises with the number of older biological brothers. But the new study found that the so-called "fraternal birth order effect" persists even if gay men were raised away from their biological families.

Study author Anthony F. Bogaert said the findings add to a growing body of evidence that links homosexuality to nature, not nurture.

"The research suggests that the development of sexual orientation is influenced before birth," said Bogaert, a professor of community health sciences at Brock University in St. Catharines, Ontario, Canada.

Bogaert and a colleague first reported the older-brother effect a decade ago. According to Bogaert, men with no older brothers have about a 2 percent to 3 percent chance of being gay. If they have three or four older brothers, the rate goes up to about 5 percent.

About 20 studies have reinforced the link between fraternal birth order and male homosexuality, Bogaert said. However, no similar link has been found in lesbians.

Bogaert said he launched his new study to better understand the fraternal birth order effect. "Is it a biological phenomenon? Or is it psychological or have to do with rearing?" he said.

To find the answer, Bogaert examined surveys of 944 Canadian men, both gay and straight, about their sexuality and their families.

The older-brother effect was constant regardless of whether the men were raised with natural, adopted or stepbrothers. It also didn't matter if they weren't raised with their biological mothers.

If gay younger brothers and older brothers don't have the same home environments, what do they have in common? "They shared the same uterus, the same womb, the same mother," Bogaert said.

His findings are published in this week's issue of the Proceedings of the National Academy of Sciences.

The next step is to figure out exactly how biology contributes to homosexuality, said Sven Bocklandt, a postdoctoral researcher at the University of California, Los Angeles, who applauded the new research.

"For me as a molecular geneticist, this study opens a new path of research into the biology of sexual orientation," Bocklandt said.

According to Bocklandt, one avenue of study would be to test the blood of mothers with multiple male sons to see whether their immune systems might be more likely to target genes linked to homosexuality.

Earlier this year, Bocklandt was co-author of a study that found that nearly one-quarter of women with multiple gay sons showed signs of genetic differences from other women.


[source]

[Menydh]

So it is a psychological disorder.

I'm glad to be the first born in my family.

[Milesian]

http://www.narth.com/

The National Association for Research and Therapy of Homosexuality.

An organisation of professionals in America who seek to prove that Homosexuality isn't purely determined by genetic makeup and who have shown that homosexuals can be succesfully treated for what basically amounts to a psychiatric disorder.

[svin]

Homosexuality gained new status in 80's (afaik) by simple voting. And it was not like 99 vs 1, but rather like 51 vs 49. Some voters were homosexuals, that's for sure.

And by the way, many serious institutes still consider homosexuality to be psychiatric disorder.

[Susano]

Crossthe "serious" out and you are right. Well, idiocy does not die out so quickly. As Ive said in the German Subforum, it just plain does not matter. One only has to ask 1) wether it is consensual and 2) wether it harms others. If 1) is yes and 2) is no, then everything needed to be said is said. The rest is a question of biological science, not of scoial or political debatte.

And the NARTH? Those people who stick homosexuals in "therapy camps" where they come out severly traumatised? Yeah, right!

[Menydh]

Originally Posted by Susano

Well, idiocy does not die out so quickly. As Ive said in the German Subforum, it just plain does not matter.

LOL!

One only has to ask 1) wether it is consensual and 2) wether it harms others. If 1) is yes and 2) is no, then everything needed to be said is said. The rest is a question of biological science, not of scoial or political debatte.

I beg to differ! It is much of a socio-political debate.

Whether they consent or not, it is clear that there is a natural disorder in homosexualism. For a healthy society one cannot allow that a disorder is publically presented as normal.

And the NARTH? Those people who stick homosexuals in "therapy camps" where they come out severly traumatised? Yeah, right!

Umh.. let me retrieve one old story..

Gay Pride.. or Hell?

Seems to me as if homosexualism in itself is traumatizing enough without the help of therapy.

[Susano]

Whether they consent or not, it is clear that there is a natural disorder in homosexualism. For a healthy society one cannot allow that a disorder is publically presented as normal.

Well, its not natural to have states and nations either. If we were to be all natural, we'd be sitting up the trees and hunting deer with wooden spears! No, that is no argument. It is wrong anyways; the existance of homosexuality among other animal species should show that is very natural. But it doesnot matter: Mankind has moved on nearly all accouts beyond its natural stage, and that is a good thing. I'd rather live in our modern times then a stone age cave, y'know? So, yeah, that is an irrelevant argument.

Now as for what a society should allow - the basic assumption must be that everything which is not forbidden is allowed. And what is forbidden must have a reason why it is forbidden. A logical reason. Murder and theft are forbidden because it hurts people, and well, if we allowed murder or theft, society would collapse. Homosexuality does not hurt people, and society does not collpase from it. So there is no logical reason to forbid it or shun it. Really, that it is all about - wether it hurts people (and thus society) and wether its consensual. A perfect logical abse for ethics instead of archaic, illogical dogmatics! Bah, I hate dogmata.

[Strengthandhonour]

From personal experience, most homosexuals I have met within my life time had some sort of struggle during childhood or a very different upbringing. I have always linked homosexuality to mental disorder because of this.

[Carnyx]

Originally Posted by svin

And by the way, many serious institutes still consider homosexuality to be psychiatric disorder.

So did my grandpa.

[Susi]

So from all this... I wonder how or why people are gay..? I mean there has to be a reason, a trigger... and these are usually psychological.. but if it is genetic, then what?

I've spoken to a few gay men online and I've only spoken to one who seemed remotely "normal", per se. I mean, other than the fact that he enjoys having a loose sphincter...

[Menydh]

Originally Posted by Susi

So from all this... I wonder how or why people are gay..? I mean there has to be a reason, a trigger... and these are usually psychological.. but if it is genetic, then what?

I suspect that there is no just one type of trigger for homosexual orientation. The starting article tells of a biological factor. This argument looks weak just by itself. Unless there already exists a genetic predisposition to it.

The psychological or sociological factor can be important too. It is said that the likelihood for homosexual behaviour of a man raised in a home environment dominated by women is higher. This sounds plausible to me. At an early age to tend to imitate what you see around you and overtime this develops as a trait of your personality.

That should make us think then of the increased likelilood for homosexual behavious in a child raised by a gay couple.

A trigger to which all latest research is pointing to is genetics. See the article after this post.

I've spoken to a few gay men online and I've only spoken to one who seemed remotely "normal", per se. I mean, other than the fact that he enjoys having a loose sphincter...

I heared from a doctor that when they come to an old age, their sphincter becomes so loose that they see themselves forced to wear nappies!

What I still don't understand is how on earth they can find any pleasure in it. There must be some kind of masochist disorder involved there.

[Menydh]

Is there a homosexuality gene?

PhysOrg.com
December 7, 2006

Although biologists are still far from answering this question, scattered evidence for a possible gene influencing sexual orientation has recently encouraged scientists to map out a guide to future research. Because many possibilities for such a gene exist, scientists Sergey Gavrilets and William Rice have recently developed some theoretical guidelines and testable predictions for explaining the evolutionary causes of homosexuality.

“During the 1990s there was a short surge of interest by a small number of labs in finding major genes that might mediate homosexuality,” Rice told PhysOrg.com. “However, for a variety of reasons, this effort waned by the turn of the century. I think that—when studying humans—many people shy away from studying sexual phenotypes in general and homosexuality in particular. Much of Sergey's and my motivation in writing our paper was to rekindle an interest in studying the genetic basis of homosexuality. I personally think that if a firm genetic foundation for homosexuality in humans were established, then many people would view this fascinating human phenotype more objectively.”

During the past several decades, scientists have discovered some interesting patterns that may point toward genetic causes of homosexuality. Among the findings is that male homosexuality appears to be inherited more often from the mother than the father (Pillard). Also, natural selection might maintain a gene that may decrease the fecundity of one sex because the same gene also increases the fecundity of the other sex. In fact, recent data shows that female maternal relatives of gay men have higher than average reproduction capacity (Camperio-Ciani).

Another interesting result from previous research is that a male’s chance of homosexuality increases with the number of biological older brothers he has—even when he grows up away from his older male siblings (Blanchard and Bogaert). Scientists explain that, with each male fetus, a mother develops an increased immunization to an antigen produced by the male fetuses, and this antigen likely plays a role in masculinizing the brain.

These studies and others—while unable to point to a specific gene—do point to the idea that homosexuality may be inherited through a polymorphic gene, which is a gene that has more than one different form, and can exhibit either form. Studies have shown that this gene inheritance must be more complex than for common Mendelian traits.

To take the next step, Gavrilets and Rice have developed several mathematical models that make contrasting predictions for the possible factors responsible for the polymorphism of genes influencing homosexuality. Hopefully, the predictions generated by these models will guide future tests and help zone in on the correct genetic characteristics involved in sexual orientation. As Rice explains, past research has shown the complexity inherent in determining the cause(s) of homosexuality.

“We know that homosexuality (gay or lesbian) can be caused by simple genetic changes in fruit flies, and since so many reproductive and neurological genes are shared by flies and humans, it seems highly likely that there are major genes influencing homosexuality in humans,” said Rice. “However, we also have firm evidence for a birth-order effect on male homosexuality, and discordance in the expression of homosexuality of identical twins, so clearly there is also an environmental influence on the trait.”

Gavrilets and Rice identify two main factors that may explain the polymorphism of a gene (and how the gene spreads): overdominance and sexual antagonism. Overdominance refers to phenotypes that come from heterozygous genes, and the advantages promoting genetic variation. Sexual antagonistic traits are those that are advantageous in one sex, but may cause homosexuality in the other sex. For a variety of different gene inheritance patterns, the scientists provide mathematical models that require, in essence, that the benefits for one sex must outweigh the costs for the other sex.

In their study, Gavrilets and Rice make predictions for the likelihood of certain types of genes (e.g. autosomal or sex-linked, recessive or dominant, with small or large effects) favoring either overdominance or sexual antagonism under different conditions. However, many possibilities remain, and research into each one will determine how well they satisfy the requirements provided in this study.

“The research so far that I think is most illuminating on this topic are the studies showing that homosexuality can have a simple genetic foundation in fruit flies,” said Rice. “I think that it is too early to decide which of our models (or one yet to be formulated) is most feasible. However, based on the abundance of sexually antagonistic variation found in fruit flies, the sexually antagonistic variation seems like a probable candidate process leading to polymorphism for homosexuality.”

Citation: Gavrilets, Sergey and Rice, William R. “Genetic models of homosexuality: generating testable predictions.” Proceedings of the Royal Society B (2006) 273, 3031-3038.


[source]

[Menydh]

In this earlier article they attempt to answer a question that many of use may have asked ourselves at one time or another: "if we put all homosexuals on an island, isolated and let them there to breed themselves out, would the cause for homosexuality disappear?"

Apparently, no. Although the adduced reasons are not all that convincing. If at all.

Survival of genetic homosexual traits explained

New Scientist
October 13, 2004

Italian geneticists may have explained how genes apparently linked to male homosexuality survive, despite gay men seldom having children. Their findings also undermine the theory of a single “gay gene”.

The researchers discovered that women tend to have more children when they inherit the same - as yet unidentified - genetic factors linked to homosexuality in men. This fertility boost more than compensates for the lack of offspring fathered by gay men, and keeps the “gay” genetic factors in circulation.

The findings represent the best explanation yet for the Darwinian paradox presented by homosexuality: it is a genetic dead-end, yet the trait persists generation after generation.

“We have finally solved this paradox,” says Andrea Camperio-Ciani of the University of Padua. “The same factor that influences sexual orientation in males promotes higher fecundity in females.”
Relative differences

Camperio-Ciani's team questioned 98 gay and 100 straight men about their closest relatives - 4600 people in total. They found that female relatives of gay men had more children on average than the female relatives of straight men. But the effect was only seen on their mother’s side of the family.

Mothers of gay men produced an average of 2.7 babies compared with 2.3 born to mothers of straight men. And maternal aunts of gay men had 2.0 babies compared with 1.5 born to the maternal aunts of straight men.

“This is a novel finding," says Simon LeVay, a neuroscientist and commentator on sexuality at Stanford University in California. “We think of it as genes for ‘male homosexuality’, but it might really be genes for sexual attraction to men. These could predispose men towards homosexuality and women towards ‘hyper-heterosexuality’, causing women to have more sex with men and thus have more offspring.”

Camperio-Ciani stresses that whatever the genetic factors are, there is no single gene accounting for his observations. And the tendency of the trait to be passed through the female line backs previous research suggesting that some of the factors involved are on the male “X” chromosome, the only sex chromosome passed down by women. “It’s a combination of something on the X chromosome with other genetic factors on the non-sex chromosomes,” he says.
Immune system

Helen Wallace, of the UK lobby group GeneWatch, welcomes the new research that moves away from the controversial single-gene theory for homosexuality. “But it’s worth noting that the data on the sexuality of family members may be unreliable, so more studies are likely to be needed to confirm these findings,” she says.

Even if the maternal factors identified by Camperio-Ciani’s team are linked with male homosexuality, the research team’s calculations suggest they account for only about 14% of the incidence.

Their findings also support earlier findings that when mothers have several sons, the younger ones are progressively more likely to be gay. This might be due to effects changes to the mother’s immune system with each son they carry.

But Camperio-Ciani calculates the contribution of this effect to male homosexuality at 7% at most. So together, he says, the “maternal” and “immune” effects only account for 21% of male homosexuality, leaving 79% of the causation still a mystery.

This leaves a major role for environmental factors, or perhaps more genetic factors. “Genes must develop in an environment, so if the environment changes, genes go in a new direction,” he says. “Our findings are only one piece in a much larger puzzle on the nature of human sexuality.”


[source]

[Pagandawn]

Let the Gay be Gay.

6-7%? of the population are gay. It is the same for all races. It is surely a genetic reason for this. It is not contagious. The last thing on earth an hetero wants is homolove.

I think homophobia is a Christian problem.