Gayness may not be in our genes, but in the molecules that regulate them. New research suggests that epigenetic factors -- chemical "switches" attached to genes that turn them on or off -- are a more plausible heritable mechanism behind homosexuality than DNA itself.
Non-genetic changes to gene expression are called epi-marks, for epigenetics, the field of research dealing with the molecular on/off switches. Epi-marks are normally erased between generations, but there's recent evidence that they're sometimes passed from parent to child.
Researchers at the National Institute for Mathematical and Biological Synthesis (NIMBioS) looked at how epi-marks that influence testosterone sensitivity in the womb might contribute to homosexuality. Late in pregnancy, natural variations in testosterone levels can alter a fetus' sexual development. Sex-specific epi-marks protect female fetuses from masculinization in the presence of too much testosterone; boys are protected from feminization if too little testosterone is present.
According to computer modeling by the group, testosterone-buffering epi-marks passed from a parent to an opposite-sex offspring may result in the reverse effect: Girls who inherit sex-specific instructions from their fathers will be partially masculinized, while boys who get epi-marks from their mothers will be partially feminized. In this model, homosexuality occurs when stronger-than-average epi-marks influencing sexual preference from an opposite-sex parent escape erasure and are then paired with weaker-than-average sex-specific epi-marks produced in opposite-sex offspring.
The model suggests that sex-specific epi-marks have survived because they're highly beneficial for parents' fitness and are only infrequently passed on to offspring, where they may reduce reproductive fitness.
"The study provides a very interesting, but as yet untested, genetic mechanism for the evolutionary maintenance of human homosexuality," says Nathan Bailey, an evolutionary biologist at the University of St Andrews in Scotland who was not involved in the research. "We are going to have to wait until more evidence is in, but I do think it would be exciting to know whether epi-marks contribute to the expression of sexual orientation in humans."
Study co-author Sergey Gavrilets, a professor of ecology and evolutionary biology and mathematics at the University of Tennessee, Knoxville, and associate director for scientific activities at NIMBioS, says there could still be a "gay gene" or genes, but that there are problems with the idea: "Nobody has been able to present solid experimental evidence for this in spite of significant effort."
The search for genes that control sexual orientation is based on increasing evidence of a strong genetic component. Studies clearly show that homosexuality runs in families, with an increased rate among siblings and the maternal uncles of gay men, according to a 2011 review.
A study published online just last week by Italian researchers Andrea Camperio Ciani and Elena Pellizzari found that the maternal aunts and grandmothers of gay men have more children than those of straight men. A few years ago, Ciani used genetic modeling to explain the 2004 finding that sisters and maternal aunts of homosexual men have more children than the females in the maternal line of straight men. According to that model, at least one unknown gene on the X chromosome predisposes female carriers to higher fertility and male carriers to homosexuality. "The genes evolved for the fecundity benefit in females, at the reproductive cost of an increase in homosexuality in males," Ciani explains.
Gavrilets says the theory is compatible with his. Both "provide an example of sexually antagonistic selection, when some traits are maintained in the population -- in spite of being deleterious in one sex -- because they are advantageous when expressed in the other sex," he says.
Meanwhile, a study published online yesterday provides what may be the first evidence of a direct reproductive benefit for same-sex sexual behaviors in males. Researchers at the University of Frankfurt found that female Atlantic mollies, a type of fish, may switch their usual preference for colorful males to drab males after observing the less-desirable fish engaging in sexual behaviors with their more vivid counterparts.
The researchers theorize that bisexuality directly benefits male Atlantic mollies thanks to the phenomenon of female mate choice copying, in which females prefer males that they've seen engaged in sex. ("Displaying mating behavior conveys information not only about a male's readiness to mate, but also mate quality, as performance is associated with costs," the authors write.) Usually female mate choice copying occurs after observing heterosexual couplings, but this study demonstrated the same result with same-sex partners.
Female mate choice copying has been observed in animals ranging from fruit flies to birds to humans. Evolutionary biologist David Bierbach, the study's lead author, says it can't be ruled out as a potential driver of male bisexuality in our species.
Evolutionary adaptations, of course, aren't the whole picture. Heritable factors, whether genetic or epigenetic, only explain perhaps 20 to 50 percent of variation in sexual preferences, Gavrilets says. "Recent studies suggest that sexual orientation (as nearly all behaviors) is based on the genetic constitution of an individual, as well as on environmental factors the individual experienced in certain life stages," Bierbach says. "Nature and nurture."
Bailey adds, "The idea of a 'gay gene' is overly-simplistic. Biologists know that complex traits such as sexual orientation develop from interacting genetic and environmental effects, and [the NIMBioS] study doesn't change that view."
Oh get over it you idiot.. how about you remover yourself?
This is very interesting... If this proves to be true a lot of those religions that stress propagation (which also tend to be very homophobic) ironically may be contributing to higher percentage of gay people ... (Maybe it's built in counterbalance to fight over population?)
+1 to Phaggamemnon's suggestion
I also find this very interesting. I also like that, as opposed to some other recent Popsci articles, this article isn't inflammatory. It strikes a neutral, factual tone, which I appreciate.
The North Korean Leader Kim Jong-un is gay. He's attracted to male donkeys.
All behavior is a choice. Though what influences behavior may not be.
Ethics should not be based on what influences behavior.
There are also genetic connections to violent behavior, but we do not condone that.
Wow at the ignorant people...
And your moral code is a choice. And so is mine.
"...The study provides a very interesting, but as yet untested, genetic mechanism for the evolutionary maintenance of human homosexuality," says Nathan Bailey, an evolutionary biologist at the University of St Andrews in Scotland..."
"...Study co-author Sergey Gavrilets, a professor of ecology and evolutionary biology and mathematics at the University of Tennessee, Knoxville, and associate director for scientific activities at NIMBioS, says there could still be a "gay gene" or genes, but that there are problems with the idea: "Nobody has been able to present solid experimental evidence for this in spite of significant effort..."
... The article is interesting, but nothing factual yet, so not helpful or useful either.
"Live and let Live"!
ive made similar statements that this could be one reason for homosexuals. im a supporter for gay rights. my cousin is fiercely against it citing biblical reasons. mainly it is an abomination against god will or whatever. guess what i just posted on his wall :)
I hope they do not decide to shut off the "gay gene." The world would become much less fabulous.
@Robot, does Kim Jong-Un go to Mexico for Donkey sex parties?
@ beefymclovin, Same here. At the University of Az there was Brother Jed screaming that homosexuals are wrong and should kill themselves. Some pretty hard stuff. The funniest thing I saw him say and do was display electrical sockets and plugs and show how sockets and sockets don't go together and neither do plugs fit with plugs.
This picture is disgusting, please change it, homosexuality is a mental disorder, not a genetic malfunction
In reality, I have no idea what Kim Jong-Un life style choices are; he just appears to be an a#s to the world and his own peoples.
The above illustration might have been taken from an CPR illustration. ;)
calebscape808 - You are correct and it was listed as such for many years (and later removed when social pressures on the psycological community caused them to change their stance on the issue).
Whether you believe that homosexuality is an abomination or perfectly acceptable, it is clearly not "normal" being a minority of any population and is also heavily influenced by sociatal factors.
I perfer to think of it like taste preference. Some tastes we perfer through biology (sugar and fat are good). Some tastes we perfer through culture / social exposure. Some tastes we perfer due to individual expression.
Thus, while there is a great deal of choice involved, they are not simple yes/no choices, but an amalgamation of choices leading to a conclusion that is difficult to adjust.
At the end of the day, however, all behavior is choice - so any manifestion of sexuality is optional. Also, much of the mental side of sexuality is variable. You were not born desiring to have sexual relations - that changed over time. Most people with deviant sexualities will also admit that those changes developed over time (porn, violent porn, to snuff films, to necrophilia - or chasing barely 18 down to almost 8).
So, when the homosexual says that they were "born this way" they are clearly incorrect (I doubt they remember their birth, must less which gender they planned to copulate with). They developed into it over time through culture, thought, and permission of the will.
When they say that being homosexual isn't a choice, they are correct that they didn't "choose" to be gay. That is not the same as proving, however, that they "had" to be gay or would have been gay if raised in a different environment.
As the changes in ideals of beauty have shown us, much of our perception of attraction is culturally influenced.
Why go with the current or swim against it, is a question? It is with ease I can allow myself to go with the flow, but it takes mental or physical effort to swim against the current. To what motivates me to swim against the current; the possibilities are endless. ~ Robot.
Again it should be pointed out to all the skeptics, if homosexuality was a choice, then heterosexuality would also be a choice. Did all of you straights choose to be straight? I could never have chosen a different sexual preference than the one I ended up with because the primal "urge" is just too strong.
@Bagpipes100: I am so sick of people like you trying to compare violent acts with homosexuality. Even one of our supreme court justices has recently done the same thing.We don't condone violence because it directly effects innocent people.What two consenting adults do in there own home and life don't effect anyone but them.So according to you even if there was some genetic trigger that causes them to be gay they still don't have the right because they could choose to be with the opposite sex even if they were not attracted to them and could not ever love them. So they are wrong because they would like to be happy. What if everyone decided that you should have a same-sex partner. You would be miserable and could not love them but that's OK because everyone else knows what is best for you and society. You probably wouldn't be so quick to spew that ignorant BS if so.I am not trying to bash any one and i am straight but It is less ethical to impose your will on people for being the way they were born to be. People with ideas like this are what is wrong with the world today. Why cant you worry about things that actually pertain to you instead of trying to ruin others life because you cant handle the things going on in your own life
Well I can tell the chubby dorito coated fingered basement dwellers are out in force today. While Oaksparr's comment is long and seeming well written it's as intelligent as a pile of bricks. If you think environment IS a factor then people can be changed.. that's clearly not the case... ie. twins where one is gay and the other is not. Also the case of both twins being gay is about 75% of the time well above the 25% threshold used to determine genetic correlation of inherited traits, attributes or diseases. In addition to that the environmental argument goes out the window because gay people are of every race, class, social group, and etc. Typically if something is "environmental" it's found in specific populations not all over the place like homosexuality. Also as the years roll on and more research is done I am sure bi-sexuality as stated in the article above will be found to have a much larger presence then anyone realizes.
Surprise, we humans come in varieties of personalities.
In reality this is not news, now get over it and most important learn get along.
Funny name lol. I like it.
It seems interesting that a large population of homosexuals talk in a certain tone and manner. Ever judged someones sexual orientation based off of their voice? To me this seems to hint at a genetic factor.
This "study" will never be proven true. For one, it doesn't leave open discussion for bi-sexuality, and since Transgenderism has been proven to be genetic, who cares?
Interesting study. Epigenetics is fascinating. The epigenome is affected by everything from diet to environment to lifestyle choices. And those traits can be passed on to our progeny. Whether or not homosexuality is determined by epigenetic changes remains to be seen. Epigenetics or no, the finding that homosexuality tends to run in families doesn't seem surprising. Alcoholism and other addictions, abuse, and other counterproductive behaviors tend to run in families too. Perhaps there's an epigenetic component in these too. If so, it has been demonstrated that people who change their behavior in response to a particular predilection (e.g.; ending a cycle of abuse or addiction) may also pass on that changed behavior to their children. Our destiny is not determined by what we're born with; it's determined by what we choose to make of ourselves.
Gay Switch! Hahahaha
But, in all seriousness! This is a dark ages type of scientific stupidity right here. Can anyone tell me why money that could be used for something that could actually benefit the world is being used to find a gay gene? A gay gene?! What's next? Are they going to look for the gene that causes me to like the color green? How about the douche bag gene that I seem to possess. For all the dumb ass ways of trying to win an argument. For instance. Oh, this gene here makes me susceptible to liking explosives, and enjoying the company of sheep's on a cool desert night. Nope! You enjoy those things, because your woman have no rights which also leads to your sexual frustration. Your reward is 2,500 virgins, or some shit. Shouldn't that say something about your priorities? Ok, that has little to do with homosexuality, but the point is everyone is influenced by life events. I have never had problems with anybody who was a little dandy, but the reasons you like men is likely no different than the reason I like green, or Hispanic woman. I'm white for the most part, so I really doubt I'm programed with a gene that determined this. So, everybody just leave everyone else alone, and shut your cock suckers. Well, unless you like that, so do whatever floats your boats.
;D Bye, everybody!
If you're not gay, why do you care? If you're gay, why care what others think? I'm tired of people having an opinion on what doesn't concern them.
Genes govern how a person can react with their environment (at all levels). It's a spectrum of probabilities that are laid out at birth. For instance, there are genes that predispose people to be more violent or susceptible to drug abuse and addiction. But in the absence of such environmental factors such as child abuse or drug exposure, these genes do not illustrate their predisposition. The same goes for positive traits....actually the same goes for ALL traits, just to various degrees and probabilities. Understanding this is difficult but eye opening. Genes interact in extremely convoluted ways, that can take a lifetime of scientific study to fully appreciate. It is important to understand how we are merely vessels for our genes, whether they be detrimental, beneficial, or neutral, they have created complex organisms such as humans through natural selection. Epigenetics is an even further level of complexity in how genes interact with environment. It is important to realize when people say there is a gene for "this" and a gene for "that," it is not always that simple. Genes can be necessary for certain phenotypes or simply part of a group of genes that contribute to a phenotype, or simply a modulator of that phenotype. It is in no way irrational to consider the role genes, their interactions, and there regulation of expression play in the phenotype of homosexuality.
In other words, genes send you into the world with probabilities for certain phenotypes (at all levels, from the cumulative effects of proteins to the behaviors human beings express). However, these probabilities can both be subject to change or be deterministic in nature depending on the environmental exposure of a particular individual.
In other other words...Its all about nature AND nurture that determines who you are.
Why put a label on anything? Just do what feels good. As long as it's consensual it's all good.
"I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours"
- Stephen Roberts
Mmmmm, kisses to all and to all Merry Christmas!!!