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Group of Scientists Believe They Have Unlocked Hereditary Question of Why People are Gay

A group of scientists from the National Institute for Mathematical and Biological Synthesis say they believe they have the answer to why people are gay, and believe it is an "epigenetic" one linking fathers to lesbian daughters and mothers to gay sons. And they say they can prove whether their theory is right within six months, US News reports:

GenomeLong thought to have some sort of hereditary link, a group of scientists suggested Tuesday that homosexuality is linked to epi-marks — extra layers of information that control how certain genes are expressed. These epi-marks are usually, but not always, "erased" between generations. In homosexuals, these epi-marks aren't erased — they're passed from father-to-daughter or mother-to-son, explains William Rice, an evolutionary biologist at the University of California Santa Barbara and lead author of the study.


Rice and his team created a mathematical model that explains why homosexuality is passed through epi-marks, not genetics. Evolutionarily speaking, if homosexuality was solely a genetic trait, scientists would expect the trait to eventually disappear because homosexuals wouldn't be expected to reproduce. But because these epi-marks provide an evolutionary advantage for the parents of homosexuals: They protect fathers of homosexuals from underexposure to testosterone and mothers of homosexuals from overexposure to testosterone while they are in gestation.

"These epi-marks protect fathers and mothers from excess or underexposure to testosterone — when they carry over to opposite-sex offspring, it can cause the masculinization of females or the feminization of males," Rice says, which can lead to a child becoming gay. Rice notes that these markers are "highly variable" and that only strong epi-marks will result in a homosexual offspring.

Adds Rice: "We've found a story that looks really good. There's more verification needed, but we point out how we can easily do epigenetic profiles genome-wide. We predict where the epi-marks occur, we just need other studies to look at it empirically. This can be tested and proven within six months. It's easy to test. If it's a bad idea, we can throw it away in short order."

More here.

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  1. I'm sure the religious wrong will have something to say on this finding.

    Posted by: Peter | Dec 11, 2012 6:27:02 PM

  2. *sigh*

    I'll try again. FOR EXAMPLE, the index finger and the ring finger for MEN are usually the same length. In WOMEN, the ring finger is longer than the index finger. That difference is somewhat determined by exposure to hormones during fetal development.

    The ring fingers of GAY MEN are often longer than the index finger, which is more typically found in straight women. (The reverse is also true of lesbians and straight men having ring and index fingers of equal length.)

    It's THAT kind of trait they mean when they say "feminization," NOT behavioral traits like a lisp or a strange affection for Barbra Streisand!

    Studies have shown similarities in brain structure between straight women and gay men, which is not to say that gay men have "women's brains," but that there may be a similarity in how we process information. Nothing more.

    You can still play rugby, shoot a gun, f*rt at the dinner table, or whatever other behaviors you see as traditionally "masculine."

    Posted by: Caliban | Dec 11, 2012 6:30:30 PM

  3. @Caliban You have masculine and feminine digit ratios mixed up. Men's ring fingers tend to be longer than their index fingers. Women's index and ring fingers tend to be even. Moreover, the research on gay men's finger ratios are inconsistent, with most not finding significant differences between gay and straight men. (This isn't true of lesbians and straight women, though.) In fact, some research indicates that some gay men are more masculinized than straight men:

    "2D:4D ratio of homosexual men was not significantly different from that of heterosexual men for either hand (P > 0.09.

    "Our results suggest that events before birth (or even before conception in the case of older brothers) influence human sexual orientation. The masculinized right-hand 2D:4D ratio in homosexual women may reflect fetal androgen levels that are slightly higher than in heterosexual women. Homosexual men without older brothers have 2D:4D ratios indistinguishable from heterosexual eldest sons, indicating that factors other than fetal androgen (such as genetic influences8, 9) also contribute to sexual orientation. Finger measures indicate that men with more elder brothers, including those men who develop a homosexual orientation, might be exposed to greater than normal levels of prenatal androgen.

    "Although hyper-androgenization of homosexual men might not fit some cultural expectations10, homosexual men display several hyper-masculine characteristics, including a greater mean number of sexual partners in a lifetime than heterosexual men, who in turn report more sexual partners than do women of either orientation. Furthermore, reports that adult homosexual men have more circulating androgens (ref. 11, but see ref. 12), larger genitalia13 and more ‘masculine’ auditory evoked potentials than heterosexual men14, are consistent with at least some homosexual men being hyper-androgenized."


    Posted by: Kyle | Dec 11, 2012 6:42:48 PM

  4. @Kyle, thanks for the correction. That's what I get for paraphrasing things I read a long time ago without double-checking!

    The main point I was trying to make is still valid. When the scientists of this study say "feminization," they don't being effeminate, a "sissy" or whatever (not that there's anything wrong with that). They're talking about biological traits, not behavioral traits.

    Posted by: Caliban | Dec 11, 2012 6:52:00 PM

  5. @Caliban Your description of "feminization" is wrong. The theorists who use the term are making only a few assumptions:

    1) Men's attraction to men is etiologically identical to women's attraction to men.
    2) Archetypal or ordinary male development results in attraction to women, hence "masculinization". Likewise, archetypal or ordinary female development results in attraction to men, hence "feminization".

    All that the term implies is that gay men are attracted to men and that this attraction evolved in females. Researchers look at other sexually dimorphic traits (like finger ratios or spatial skills) in gay men to find traces of a "feminization" process in individuals where it wasn't localized to sexual attraction.

    Posted by: Kyle | Dec 11, 2012 7:02:25 PM

  6. masculinity is like "Cool" - to be it one must first stop trying to hope that others think they are it.


    Posted by: LittleKiwi | Dec 11, 2012 7:04:30 PM

  7. I think the whole genetic theory could be fact but there "story that looks really good" seem very unlikely because it works under the assumption that all lesbians are butch and all gays are feminine. It's like saying a person's gay because of the way they dress.

    Posted by: Joseph | Dec 11, 2012 7:15:36 PM

  8. "Masculinization" and "feminization" are really misleading and culturally loaded terms. Female reindeer aren't less "feminine" because they have antlers, though they may have been inherited from male reindeer. Likewise, cave lion males (cave lions are an extinct subspecies of lion) weren't any less "masculine" than other lion males because they were maneless.

    Heck, men's nipples are owed to "feminization". It's really meaningless.

    Posted by: Kyle | Dec 11, 2012 7:21:41 PM

  9. "Also, I'm betting Rick isn't going to be pleased with the whole gays-as-feminized-males bit."

    Indeed he is -- and with good reason for a change. As we all know "Rick" despises anything "effeminate" in gay men. Fine. He can have all the "straight-acting, straight-appearing" bozos he wants. I don't se the world that way. Gay men come in all shapes, sizes and styles. So do staight men. That these "scinetists" are seeking a "cause" for gayness clearly indicated the rigidly ideological nature of the project. Cause where there's a "cause" there's a "cure."

    No "cause" for heterosexuality is there?
    Well I'M the "cure"!

    Posted by: David Ehrenstein | Dec 11, 2012 7:26:07 PM

  10. why bother trying to find a "cause" for homosexuality when the most pressing issue is actively combating anti-gay prejudice, of which the root is already known?

    finding out what causes homosexuality will not help LGBT youth nor our ongoing journey to social and legal equality.

    combating anti-LGBT prejudice, however, will.

    Posted by: LittleKiwi | Dec 11, 2012 7:33:23 PM

  11. I'm pretty sure that they do not mean the sociological definitions of "masculinaztion" and "femination." In this context, I think it's safe to assume that they are talking about hormones, as that is the topic of the rest of the discussion.

    Anything that increases estrogen production/sensitivity and/or decreases testosterone production/sensitivity would be called feminizing. For example, soy is a feminizing compound. This doesn't mean that eating Asian cuisine will turn you into a woman, it just describes how it influences your body chemistry.

    Likewise, when they say that a feminized male fetus will most likely become gay, they are almost definitely talking about in utero estrogen exposure. The link between hormonal exposure in utero and homosexuality is not a new hypothesis, nor should it cause any sort of uproar amongst anyone. The biological terms are entirely different from the (loaded) sociological terms, as in a feminized male does not necessarily lead to a feminine male.

    The goal of science is to answer the questions humanity has. "Why are some people homosexual?" is no more a bad question that "Why are some people better at learning languages?" Any further understanding we can gain of our universe serves to advance science as a whole.

    As far as conservatives genetically engineering their children to not be gay, if we get to the point where our laws and scientific ethics, as well as technology, allow that, I think conservatives not having gay children will be the least of our worries.

    Posted by: OddBet | Dec 11, 2012 8:49:26 PM

  12. Agree with comment above "they had me until..."

    The article states "The masculization of females and feminization of males." Surely there are obviously masc lesbians and feminine gay men. But wtf? What about the (in my opinion) majority of gay men who are conventionally masc and women fem? They stay in the closet because it's easier for them from the start as no one suspects. The implications of this study are at once intriguing, perhaps even correct. But implying that all gay men are "feminized" and women "masc" is preposterous.

    Posted by: tjm2112 | Dec 11, 2012 9:12:41 PM

  13. @Oddbet No researcher or theorist claims "a feminized male will most likely become gay". This a wishy-washy statement, while the real development of sexual orientation has a rigorous explanation. They're talking about localized "feminization", not general "feminization". All males are likely "feminized males" in various areas to various degrees, and many a gay male was barely "feminized" beyond his sexual orientation.

    The epigenetic marker hypothesis on topic better explains the hyper-localized feminization that apparently typifies a sizeable subset of gay men than earlier simple hormonal exposure theories by allowing for a homosexual orientation to develop under normal or even excessive testosterone exposure.

    Posted by: Kyle | Dec 11, 2012 9:36:15 PM

  14. Conservatives can't call it a genetic disorder because it's not strictly genetic. And just because something is caused by genetic factors doesn't mean it is a disorder.

    For example, albinism. Albinism is a recessive trait that can be passed on from generation to generation. But just because someone is albino, does that make them mentally ill or make them any less of a human?

    Posted by: Lai | Dec 11, 2012 11:36:59 PM

  15. Some scientists are unable to distinguish between a mathematical model and a fact. And, why would passing on epigenetic marks protect the mother - or especially the father whose investment in gestation is zero?

    Posted by: nicoise | Dec 11, 2012 11:39:58 PM

  16. @KRISTIAN, yes they cured cancer

    Posted by: crg | Dec 12, 2012 12:21:40 AM

  17. @Kyle

    Like I said, the researchers are using "masculinization" and "feminization" to refer to the influence of hormones. In the press release for the study, they outlined that the epi-marks influence the effect of androgen levels during late fetal development. As an example, they give the scenario of the epi-marks for a female fetus protecting the fetus from masculinization during abnormally high levels of testosterone.

    Your response to my comment seems to indicate that you did not understand what I was saying, so allow me to clarify. I was attempting to explain that feminization in the biochemical sense has nothing to do with cultural definitions of femininity, but instead relates to hormones (as per my example of soy being feminizing). So, as you see, your correction was unnecessary, since it seems that we are both saying the same thing (that feminization is not a dirty word and has a specific meaning, and that it happens to all men throughout their lives, but does not exclusively determine their mannerisms)

    As far as what I said about a feminized male fetus, I was speaking specifically to the scenario outlined by the hypothesis, not to feminization of a fetus in general. I had thought that the context would make that clear, but if it was not, I apologize.

    Posted by: OddBet | Dec 12, 2012 2:39:11 AM

  18. Being gay and femininity are separate. They sometimes go hand in hand, but as I've said before, being gay simply refers to your homosexual attraction, not how masculine or feminine you are. Give a gay man all the testosterone you want, he'll still be gay.

    Posted by: Deee! | Dec 12, 2012 4:36:46 AM

  19. I really love this article. So is this how science deniers start? A bunch of morons that have no knowledge of biology freak out about a poorly reported article about an ongoing research project. Is this how Jenny McCarthy became a vaccine nut?

    Posted by: Fenrox | Dec 12, 2012 9:50:30 AM

  20. I really love this article. So is this how science deniers start? A bunch of morons that have no knowledge of biology freak out about a poorly reported article about an ongoing research project. Is this how Jenny McCarthy became a vaccine nut?

    Posted by: Fenrox | Dec 12, 2012 9:50:37 AM

  21. Epigenetics sounds eerily like eugenics. Biology determines destiny. Therefore, if society and politics deem that a group is unacceptable, it can justify its extermination by declaring that group as genetically deficient and harmful to society as a whole.

    I know my sexuality is as natural as breathing. I am who I am. Period. I don't give a rat's ass why.

    Posted by: MJ | Dec 12, 2012 10:52:13 AM

  22. KYLE & ODDBET,

    thank you for helping me to understand this fascinating science (well, understand somewhat).

    The people who are still NOT getting the idea that the scientists are using a different definition of "masculinization" and "feminization" need to google the name "Emily Latella."

    Posted by: Derrick from Philly | Dec 12, 2012 12:11:49 PM

  23. Let's not forget the mind-boggling complexity of the question. It takes us from the biochemistry of reproduction to the neurochemistry of human desire to the social chemistry of human interactions. No single answer is likely to be "the" answer; rather it will be several answers all in combination.

    Posted by: Chuck Mielke | Dec 12, 2012 1:43:26 PM

  24. LMFAO at Kristian... Touché.

    Posted by: Stefan | Dec 12, 2012 1:48:24 PM

  25. My only concern is based on genetic screening and people using this genetic marker as an excuse for abortion on the possible sexual orientation of the child. The opposition is still strong I fear for young who will not be able to defend themselves from pregidice. I am not however against abortion because it is a woman's right to choose to give life but on the factors of health and circumstance of conception. Messy business to be sure.

    Posted by: mattie | Dec 12, 2012 3:02:51 PM

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