Homosexuality Might Develop in the Womb Due to Epigenetic Changes


Credit: Shutterstock/Anton Gvozdikov; University of California

According to a newly released hypothesis, homosexuality might not lie in DNA itself. Instead, as an embryo develops, sex-related genes are turned on and off in response to fluctuating levels of hormones in the womb, produced by both mother and child. This benefits the unborn child, however if these epigenetic changes persist once the child is born, and has children of its own, some of these offspring may be homosexual.

The scientists published their findings in the journal The Quarterly Review of Biology. Evolutionary geneticists propose that this is the reason why homosexuality didn’t fade away due to evolutionary pressure. Current research estimates that 8% of the population is gay, and it has been known that homosexuality can run in families. If one of a set of identical twins is gay, there’s a 20% chance that the other will be, too.

Homosexuality isn’t just tied to the human species. There are many species exhibiting homosexual traits, including fish and birds, and geneticists have not been able to find a gene that is responsible for sexual orientation.

Testosterone doesn’t explain everything. Female fetuses are exposed to small amounts of testosterone from their adrenal glands, the placenta and the mother’s endocrine system. At many key points of gestation, male and female fetuses are exposed to similar amounts of testosterone. Levels of the hormone can be higher than normal in females and lower than expected in males without any effects on genital or brain structures.

The authors propose that the differences in sensitivity to sex hormones result in epigenetic changes, which don’t affect the structure of a gene, but can be activated by chemically altering a gene’s promoter region. Epigenetic changes could enhance or blunt testosterone’s activity as needed.

Epigenetic changes involve alterations in the proteins that bind together long strands of DNA and can be handed down to offspring. The authors propose that homosexuality may be a carry-over from one’s parents’ own prenatal genes to resist excess testosterone, and this could alter the gene activation in areas of the child’s brain involved in sexual attraction and preference. This could explain why homosexuality persists throughout evolution, state the authors.

Going from changes in gene expression to why someone is attracted to a person of the same sex is probably a question for which science may never find the answer, states Marlene Zuk, an evolutionary biologist at the University of Minnesota, Twin Cities.

Reference: “Homosexuality as a Consequence of Epigenetically Canalized Sexual Development” by William R. Rice, Urban Friberg, Sergey Gavrilets and Handling Editor Hanna Kokko, December 2012, The Quarterly Review of Biology.
DOI: 10.1086/668167

41 Comments on "Homosexuality Might Develop in the Womb Due to Epigenetic Changes"

  1. This is all sorts of messed up. Why is it that we are trying to “explain” it?
    So now if you’re gay its your moms fault and it’s a genetic disfunction. Unify the people my a$$.

    • My mother is bisexual, my sister is bisexual, I think my brother is closet gay, I’m gay, I have gay cousins on my dad’s side, on my mom’s side, her brother is gay, my cousin is bisexual— let’s be honest here. There is a genetic trend in my family and it is likely this science isn’t meant to “explain” why homosexuality is this or that– it’s just plain facts. How a person twists the facts is another agenda.

      • I couldn’t agree more. I’m a fellow homo-sexual. My dad has two sisters each of them have a gay child. His mother’s sister has three daughters one of which has a bi- sexual son, the other daughter has an only child who I know for a fact is gay. However the rest of the family don’t. And the other daughter have two younger girls, one of which is very butch. Time will tell I could be wrong. I tell you an interesting book all if you’ve not read it yet. ‘The evolution of homosexuality’. I can’t help but feel the only time homophobia comes into the picture is when the sons of god or allah are put into the picture. Now don’t call me anti- Islam I beg of you.

        • Why are people afraid of being called anti-Islam? It is the only religion of which I am aware which currently makes it legal (in those countries which have Islamic governments) to execute people for the crime of being gay.
          Certainly not all Muslims agree with that practice, but in fundamentalist Islamic countries those moderate Muslims opinions carry no weight; only the teachings and interpretations of the Islamic religious books matter. I can’t see it as other than a dangerous religion.
          Egalitarians often accost me saying “but there are terrible Christians who murder gays also” implying thereby that there is no difference between Mohammed and Christ. But I see a difference in the teachings and actions of the two men, and, on the whole, of their modern followers also.
          I feel criticized for my opinion, but can’t see it any other way.

    • But why is it bad if it is a genetic dysfunction? Seeing as how the whole purpose of sex is reproduction, it very well could be genetic dysfunction. That doesn’t make it wrong or abnormal.

      • Now that is spring go look at a field of flowers. Some grow huge some grow small. Some do’t blossom some don’t sprout. some are different. Evolution relies of these variations to sustain the species. maybe not today but maybe in the future. Nothing is static in this world and the environment changes sometimes in our favor sometimes against. These “dysfunctions” maybe the key to adapting. This is what life has done for millions of years and will continue to do so. So it is imperativethat we learn all we can and supress nothing.

    • I don’t think knowledge would do any harm. It’s nobody’s fault. That genetics can partially explain it doesn’t mean it’s anything bad, genetics explains the colour of your hair or eyes. And, as for the environmental factor, many things are determined by how we develop in the womb.
      The more we know, the better will be for the lgtb, imho

    • Why does it have to be “fault” as if there’s anything wrong with being gay? Anyway, I agree with what you said but I don’t see it as a bad thing. I’m gay and happy.

    • There is an innate absudity in the genetic/nature argument. But this does not mean that the matter is entirely behavior-normed/nurture either. This certainly is not what those who self-identify experience. One possiblility is that the low-choleteral low-fat diets since the 70’s have had a big effect on children. Nuts? But cholesteral is a major pre-cursor for sex hormones and breast-milk is essentially saturated fat. Take 100 million woman off something during pregnancy and who knows what happens.

  2. Explaining it doesn’t say anything about whether its wrong or right. There are explanations for lots of differences in humans and we don’t then say therefore that difference is wrong. Its interesting to know about the factors that add up to make us who we are.

  3. -“Current research estimates that 8% of the population is gay, and it has been known that homosexuality can run in families.”

    What research? Where’s the link to that? Homosexuality “runs in families” that are willing to accept and love their son and daughter no matter who they love, not hid and deny it, especially to researchers.

    The article also states “homosexuality might not lie in DNA itself” – Wheres the articles that says it does? Theres no solid proof on the origins of homosexuality and is generally accepted as a fact about most species of animal. This article is contradictory, assumptive, speculative and poorly written at best.

    • The study, which you can link to from the article, explains where the researchers got their information.
      The study: “Homosexuality as a Consequence of Epigenetically Canalized Sexual Development,” William R. Rice, Urban Friberg, and Sergey Gavrilets, The Quarterly Review of Biology

      “Might not lie in the DNA itself” means in the DNA and in something else.

    • The source article has all of the right sources, if you care to read up on them. You can find them here


      or the article cited by our Staff. This article is about the possibility that epigenetic changes could affect the sexual preference of offspring. It has to do with the science, not with the moral dilemmas that stem from this.

  4. Or it cold be that its just a natural part of human sexual expression, and cultural pressures prevent it from being more openly accepted. In animals the behavior is pretty common. Twins are more likely to WANT to mimick each other, so the fact that both are more likely to be gay if one is doesn’t necessarily co-oberate this weak study.

    • How the hell would you know something like that. I’m an identical twin and guess what, I am my OWN human being. I have no desire to appear or act similar to my brother, nor do I go out of my way to not be like him. A sibling is a sibling, and that’s it. Mine just happens to look similar to me.

  5. Now there is a new type of testing known as autosomal testing, which relies on the other 22 chromosomes, the ones that are not the sex chromosomes.

  6. Over the last 45 years I have noticed a huge increase in the number of Homosexuals and have wondered why their has been such a huge increase between the 70’s and the 90’s. I believed in College in 1972, for which I was verbally abused by my Micro Instructor, that their had to be a Mutation of some sort going in the womb. This is the same Micro Instructor who I had a go around with the previous year about the effects of Partially Hydrogenated fats reacting exactly the same in Cholestrol Lab tests. So my question now is what external substance or life style, is creating the mutations in the womb. Since man I believe is primarily primed to be Hetrosexual for the main purpose of the survival of the species, then homosexuality has to be a mutantion happening in the womb also evidenced by “manish” women and Feminie Men. Is the increase use of illegal drugs by the female populace, or the increased use of Alcohol, or Pesticides in the food chain or even Corn Syrup or food perservatives and additives, antibiotics in growth hormones in Beef and Dairy Products? I do see a marked differnce in the children produced by Vegans, in my observation of only a few couples, the children tend to be more afraid or less agressive which would have been a huge negative a few thousand years ago when warring tribes were almost the norm. So it would be interesting to see a concerted effort to try and find the cause for the mutations within the womb. And no, I am not an expert who has been taught to think in the box, to be accepted by such low lifes as my former College Professors whose huge Egos were threatened by anyone like myself thinking out side of the box..And still do..

    • Thought-provoking comment…. looking at the situation, spiritually, I used to believe (there’s that tricky word on a science forum) that Homosexuality was Nature/Evolution’s natural population control, which I hypothesized to be a gene mutation that occurs by random to control the population. There is no evidence or basis behind my theory, but one inspired by some classic spiritual poetry.

      Thinking about it, it would make sense as Homosexuality occurs in many species of animals. I for one am a homosexual male and I personally feel elated to know (and believe) that my homosexuality contributes to a natural, effective, harmless, efficient population control.

      • Interesting thoughts, but I’m not sure it’s a huge form of population control at the percentages it’s at.

        I’ve seen many cited instances of fleeting homosexual behavior in the animal population, but never seen a case of an animal that exhibited only homosexual attraction from birth to death. Have you? I’m interested in that discrepancy. I also have heard very little of a deeply fixed innate orientation in antiquity & in tribes, but again, almost exclusively either bisexual, or passing homosexual behavior. Those observations seem to confirm these findings, if the hormonal conditions in the uterus are becoming more distorted as a result of androgenic (as in kraft paper mill water pollution) and estrogenic (as in excreted BCP & HRT water pollution) pollution, as some sources indicate.

      • That’s a very interesting pov. Much preferable to the prochoice option. I think I like it.

    • Vegan children are not passive or afraid. You do know plant foods are required for our survival? If anything vegan children are much healthier than the rest.

    • In the last 100 yrs the population has exploded drastically, could be the rise in homosexuality is in proportion to population level or density.

  7. Francisco Culloton | May 30, 2013 at 3:12 am | Reply

    great article although I’m not sure if i believe this is true – think this is going to take more reading up on.

  8. texas holdem strategy | August 12, 2013 at 5:33 am | Reply

    Its sick that we all the time try to “explain” it.. // analucia

    • It’s not sick to explain it. Did you think it was sick when science examined why people have blue, green or brown eyes? Or why people are born male, female or other? That’s what science does, it looks for explanations to things. Quit being paranoid.

  9. If you’re going to pretend to have a serious and “scientific” discussion regarding what occurs during embryonic, fetal, child, adolescent and adult growth and development and reproductive process (a set of topics already far too lengthy and unwieldy to apply any real science to AT ALL) it may be a good idea to, at the very least, use SCIENTIFIC rather than BIBLICAL language in expressing the “allegedly” scientific conclusions of said discussion.

    Of course as a trained scientist I will NOT call your flimsy mish-mash of tossed about ifs and maybes science OR research, but I will share this one simple fact with you. Post-conception human development takes place, at this point in time, beings in the female UTERUS, not the mystical “womb”. How on earth do you expect people to take anything you say as hard science when you use such archaic and emotive language and base conclusions on suppositions and half-baked conjecture, not true Scientific Method?

    I cannot believe this was even considered seriously, much less published.

  10. Madanagopal.V.C | October 21, 2013 at 5:34 am | Reply

    ‘Barr body’ in the egg of the woman is a dysfunctional X-chromosome,which hides itself in the egg when fertilization takes place as a non-functional one. Okay! But it does not always stays so. If Y chromosome enters the egg it will naturally try to influence it sometimes, either destroying it completely, so that more girl babies would be produced or significantly affect the fertilization with its x-enzymes. The child may develop more testosterone or more estrogen and if it happens with the wrong sex it may become a Gay or Lesbian.Depending on the degree of getting affected the child may become a Gay or Lesbian or an heterosexual when it grows. The case of the ‘Transexuals’ is different since they are XXY chromosome holders where XX expresses the faminine qualities and extra Y gives male organs growth. XXX is completely harmless since they are 100% females and XYY chromosomes are found in some hard criminals.Thus epigenic changes for Gay or Lesbian can be little bit understood as a generation defect rather than labeling them as taboos. Thank You.

    • Even though one may have a different combination of the “X” and “Y” chromosomes, it does not mean one has to act on it.

      Not all of those who have XYY chromosomes are criminals. When we are born with inherent tendencies, it does not mean we have to act upon them.

  11. I am the only gay male in my entire family…

    How is that fair?

  12. Thoughtful reader | January 27, 2014 at 10:49 pm | Reply

    You can’t deny that it raises some interesting questions. For example, what if turns out that’s its preventable. If you could prevent your child from being gay, would you? I can tell you that any man who has children would want to (I have two), regardless of what they may say in public, nobody wants their children to be gay.

    As a society, we have come to accept homosexuality. The obvious reason being that it does not appear to be something they can control, and most of us agree it is wrong to persecute someone for something that it out of their control, so despite the repulsion so many of us feel, we accept it.

    But again, what if it could be prevented? What f you could take a shot, a vaccine, if you will, and guarantee that you children would be heterosexual. Can you really, truthfully say that you would not?

    I apologize if this has offended anyone, and I do not mean to treat it as a disease, but seriously, putting our usual knee-jerk emotional reaction aside, and look at it objectively.

    If you do answer this, I’d also be curious to know if you’re over 25, and if you have children.

  13. This sentence is badly punctuated and its meaning is confused:

    “This benefits the unborn child, however if these epigenetic changes persist once the child is born, and has children of its own, some of these offspring may be homosexual.”

    The first comma should be a period. and “however” should be followed by a comma, so that it reads:

    “This benefits the unborn child. However, if these epigenetic changes persist once the child is born, and has children of its own, some of these offspring may be homosexual.”

    Perhaps the proof reader misunderstood the author’s intended meaning. The ambiguity is similar to that of the famous line by Heraclitus: “Of this account which holds forever men prove uncomprehending, both before hearing it and when first they have heard it.”

  14. has anyone considered the possibility that anal intercourse interferes with the natural hormone balance? this theory goes back to ancient china where it was observed that women who practiced anal intercourse gave birth to especially effeminate or homosexual boys.

  15. THANKS MOM!! … Really!

  16. STAN the Trans Man | April 27, 2021 at 7:21 pm | Reply

    Hey as a pregnant man does my child have a risk of developing gayness or demon loving tendencies please let me know at [email protected]

  17. Robert L Davis Jr | May 16, 2021 at 2:28 pm | Reply

    My name is Robb Angel son of Rose Trujillo and LeRoy Davis I am proud Hispanic gay male just turned 50 on 1/20/21 been with my 2nd husband Ron Angel I’m the eldest in my family of 2 my Dad LeRoy has had 3 different marriages my his first family produced 2 daughters one is Trish Davis daughter of Judith and LeRoy we have become very close over the last few years. The dna or genetics did not pass on to her but my dad’s 2nd marriage to my mom produced 2 boys in which I am Gay new from a very young age my brother Joe Trujillo turned out to be Bisexual and now my dad’s final marriage to Tina Alva who had kids already and then had with my dad a daughter Jen Alva who has had the better part of our dad’s attention and my sister is a proud Latina and a lesbian. So her we gave my dad’s 3 marriages in a nutshell . being gay was never a choice. people like Will Perkins of Colorado Springs Colorado and focus on the family which is also in Colorado Springs attempted to strip my LGBT brothers and sisters from their basic civil rights essentially making us 2nd class citizens stating we had a choice or could be cured. Well those of us in Colorado in the 90s had to fight for the right to exist the right to marry the right to be equal we still struggle for those rights today and were almost destroyed again by the idiot Trump . I am glad that in my lifetime that it’s now been proven that sexual identity is determined at birth me my brother and my step sister is proof that it’s in our dna genes our very center of who we are 1 dad 2 different mothers . I believe that it has to do more with the dad’s genes. So people like Will Perkins can go off themselves when they make those outrageous claims follow the science the only thing that bothers me know is that the scientists will try to find a way to remove the dna or genetics that defines who we are

  18. In recent years I mean 50 or so; “Homosexuality” has changed from a disease and deprabable unacceptable behavior, to what it is today. Paraded, celebrated, and accepted and encouraged by the people in charge of our schools and government. If today statistics claim 8 or 9 percent of the population is homosexual, in 50 years from now this number will only increase inevitably and it will be reconsidered again.

  19. I am a 65 year old homosexual.I would never claim the title (gay)!it’s offensive degrading and is not manly at all.To me it’s like calling someone of color a Niger.I am just as much a man as my straight male friends. I like being a man and like manly things.I have never dated a gay man. But I have had a30 year relationship with a straight man.And I wouldn’t have it any other way we didn’t plan to fall in love but it happened thank God. I love my real man.But if you call me (gay) someone getting there ass klcked

Leave a comment

Email address is optional. If provided, your email will not be published or shared.