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Various studies show that there are genetic factors that influence homosexual tendencies. Assuming that gay men have fewer children - how does this tendency continue to exist?

Noam Levithan and Dina Volodarsky, from issue 120 of the Galileo magazine, August 2008

The flag of the colors of the rainbow - a symbol of the gay community
The flag of the colors of the rainbow - a symbol of the gay community

According to the theory of evolution, an individual adapted to its environment survives and produces offspring, thus passing its genes on. In light of this, it seems that it is difficult to explain a trait such as homosexuality, which is known among many animals - octopuses, geese, deer and more.

How is it possible that homosexuals - who are likely to produce fewer, if any, offspring than their heterosexual counterparts - exist? After all, it is expected that a feature that prevents the production of offspring will disappear from the population during natural selection. In a study published in the online journal PLoS ONE, Andrea Camperio Ciani and his colleagues from the University of Padua in Italy proposed a model designed to answer this question.

Genes and sexual orientation

Although genes directly related to homosexuality in men have not yet been identified, various studies show that there are genetic factors that influence this trait. From studies on twins, for example, it became clear that identical twins have a greater chance of having the same sexual orientation than non-identical twins, a finding that indicates a genetic influence on sexual orientation. Since, as mentioned, there is evidence that genetics plays a role in determining sexual orientation, Camprio Chani and his colleagues developed several models designed to characterize the genetic factors - the gene or genes - that affect homosexuality in men, while referring to other characteristics of male homosexuality.

The researchers began the development of the models while referring to the fact that homosexual men make up only a few percent of the population, but they can be found throughout human history, everywhere in the world and in all strata of the population - hair stylists, singers, patrolmen, priests and others may be homosexuals. The trait never completely disappeared, nor did it spread in the human population. On top of that, when you look at the genealogy of gay men, you find that they have more gay relatives on the mother's side than on the father's side.

The researchers also referred to several studies, including a 2004 study led by Camprio Chaney, according to which the mothers of gay men and their maternal aunts have more children, meaning they are more fertile, than the paternal aunts and unrelated women of gay men.

Most of the models proposed by the researchers did not meet all the requirements - in some of the models the gene or genes affecting homosexuality spread in the population or disappeared altogether, and in other models the number of homosexuals on the mother's side of the family was not reflected.

The genes that increase attraction to men

The model that matched the requirements in the best way included two genes, at least one of which is on the X chromosome, a chromosome that a man has only one copy of and originates only from his mother. These genes, according to the model, increased the fertility of women, but decreased the fertility of men carrying them. This phenomenon, in which a trait increases the reproductive success of one pair at the expense of the other pair, is called sexually antagonistic selection, and it is already known in insects, birds and mammals.

Camprio Chani and his colleagues claim that according to the results of their research, it is likely that the putative genes increase the attraction to men of both women and men who carry them. This feature reduces the men's chances of producing offspring and passing their genes on to the next generation. On the other hand, in women, the chance of this increases, allowing such genes to survive in the population at a low but stable rate.

The research of Camprio Chani and his colleagues points to genetic factors that increase the chance of a man who carries them to be homosexual, without considering the additional, environmental influence on the sexual orientation - for example, the increased chance of a man being homosexual the more older brothers he has, who were born before him. However, the model found in the study presents a simple solution to the question of how homosexuality exists, as well as an explanation for the fact that the trait is more common in the maternal lineage of the homosexual man. According to the model, the genes for homosexuality have survived because they give an advantage to women carrying these genes, and the percentage of homosexual men in the population may reflect the percentage of more fertile women in the population.

It must be remembered that this study presents a possible model for an existing phenomenon, but it does not prove that homosexuality is genetic. To test the model, the genes in question must be isolated and identified.

30 תגובות

  1. My father (not Blizovsky):
    There are indeed many reasons to think that homosexuality is genetic, but even in your words you brought explanations that are not genetic.
    It seems to me that there is no dispute (among scientists) that homosexuality is innate, but - as you also mentioned - one of the reasons can be rooted in the environment that the fetus finds in its mother's womb, and you will agree with me that this environment does not affect its genes.
    Also all the physiological details you brought (which I have neither the knowledge nor the tools to test their correctness) are irrelevant because even if homosexuality is genetic, this does not mean that natural selection will encourage physical adaptations in favor of homosexual relations because it does not "gain" anything from it - a person who does not produce offspring does not He will bring them whether he encounters feces or not.
    I'm not saying that the phenomena themselves don't exist - I'm just saying that even if they do exist - their cause is not a natural choice for adapting the body to homosexual relationships. Their reason must be different.

    I actually agree with your definition of homosexuality as a disease but I do not agree with your opinion in general.
    Why do I agree with the definition of homosexuality as a disease?
    Because for the language to be useful, a simple and understandable definition of words is necessary.
    What is a disease?
    One can try to define a disease by specifying all the phenomena we call a disease. That is - create a list that says measles, rubella, polio, anthrax...and more).
    This is of course not a useful definition - especially when with the development of science we would like to change the list.
    A disease can be defined as something that causes a person suffering, but how do you measure suffering? There are people who suffer when someone on their side does not observe the religious laws and I also came across a person who said that the fact that he had muscular dystrophy made him see the world differently and he is simply happy that he had it.
    I think the closest objective definition to the original intuition after the word "disease" is "an unusual trait that impairs the chances of the genes of the organism carrying it to survive".
    In this sense - homosexuality is a disease.
    Those who have followed my comments in the past know that I have always come out against attempts to harm the dignity of homosexuals or, mercifully, to observe the religious mitzvah and kill them. So how does it work out?
    This works out because, in my opinion, the fact that a person is sick with any disease, whether it is incurable or not, should not be linked to the value of the person.
    We have a tendency to make such a link and the evolutionary origin of this tendency is also clear. This is a private case of the phenomenon called "selection of partners" (and I suggest those interested to note that it is exactly the opposite of what many identify with the principle of respect).
    In light of this tendency, most of us also do not want to be classified as "sick". This is also clear for the same reason.
    I think that as a society that is also aware of the moral order of "Do not do to your friend what is hateful to you" we should try as much as we can to detach ourselves from the tendency to associate illness with a general decline in value.
    I am not saying that this tendency is unacceptable in the context of choosing partners, but in any other context this tendency is simply a harmful byproduct.
    Please note that in the special case of homosexuals, the decision is particularly easy because in my opinion - except for the fear of the reaction of those around them in matters unrelated to choosing partners - homosexuals actually prefer to live outside the closet and are not at all harmed by the fact that heterosexuals do not choose them as partners.
    So much for the long story about the classification of homosexuality as a "disease".

    Now for the healing thing:
    First of all, you should be clear, Hugin, that there is no mental way to eradicate a genetic disease because we cannot change our genes.
    I do not deny that our mental state has an effect - sometimes decisive - on our health - but this is true only as long as it is about diseases that originate outside the body and can also affect the rate of development of a disease that originates from genes.
    It is, of course, possible to control sexual behavior without being cured, but what's the point? It just makes a person suffer.
    If a homosexual wants - for environmental reasons - to act contrary to his innate tendency - nothing prevents him from doing so (although, in this case, he/she must share the news with his/her spouse to allow them to take this fact into account) but most homosexuals are not They want that and, in my opinion, there is no justification for pressuring them to act differently than they want.
    By the way, Hugin, regarding your response to my father (yes Blizovsky), it does not match a sentence that I remember you saying elsewhere and that your imagination is not subject to reality but the opposite.

  2. my father
    I didn't say that I have an influence on nature, but that I reflect it on its most beautiful side
    And to his honor!!! Because I am already free from him, and so are you, whether you like it or not, it is so! And you must sanctify yourself
    For his sake - with great honor for him!

    I wish you would understand my words, I wish...


  3. Very dear Yehuda, for the voice of my dear father in the head.
    As soon as you use the ratio of the majority to say something in order to justify or strengthen your words, this shows that your position is not 100 percent secure in your view. Indeed, all those who only see a part of the total potential, they need the opinion of the majority in order to strengthen their point.
    Which is not the case locally, who sees 100 percent in myself and I don't need your reinforcements.
    But, but, this is not true at all because then the question arises, what is your hundred percent worth with people who do not serve the whole? And if there is no one else who sees like you, all your knowledge will be lost forever..
    But what luck!! How fun it is to have "Yehuda" who gives me a little glimmer of fun from time to time.
    So Yehuda, continue to attack me in a good atmosphere, as far as I'm concerned, you've mobilized the whole company...yours against me
    or for the benefit of the deep insight.
    Just do me and yourself a small favor: don't get lost in overly blind male pride...because then...the mass in the universe will justify the side we both oppose so much.

    Hugin.."and family pride" etc..

  4. Dear Hugin

    I'm the last person to subject you to peer pressure. And to justify my words I say another statement:-

    Science commentators believe in the existence of dark mass!

    Believe me Hugin, most of them believe. So what?
    Sabdarmish Yehuda does not believe in the existence of the dark mass.
    What is good about science, that it cannot be forced, not even democratically. A man by his faith shall live.

    and my father
    Why do you think Hugin has no effect on nature. You are wrong!
    I also have an influence on nature, you do, and certainly Michael does,
    Everyone has an effect on nature and even a great one!
    Have you heard of the butterfly effect?, flapping wings that will cause a hurricane?

    Good signature our Hugin
    Good signature, my dear father
    I will send you my article shortly. Prepare yourself mentally.
    Good signature to all my readers and science commenters!
    Sabdarmish Yehuda

  5. To Judah
    It seems again, that you did not read the previous references I gave to this matter.
    Sometimes I have "strange" expectations. At least from the company that thinks they are intellectuals on the science website! Treat my response more seriously.

    And pay attention to what you just wrote!" Most of the science respondents do not treat homosexuality as a disease. Period."
    Tell me, what kind of social pressure are you currently trying to subject me to? Huh??

    It is permissible to think on the "Hidan" website. It is not possible for any kind of affiliation to neutralize freedom of expression. And worst of all
    The personal responsibility (even if not in a primary circumstantial relationship) for a healthy mind...and everything that comes out of it operates from it.
    There are situations in which belonging does not exempt from personal responsibility. And it doesn't matter at all what organizations they do for, what politics, etc.!

  6. to hug
    Why cure? After all, a homosexual is not sick. Would you tell Ginger to heal himself? For a person with an iter on his right (left) hand, he will heal his right hand?
    We will be more extreme. Suppose they find a gene therapy that will "cure" homosexuality. Should a homosexual man become a womanizer, I will still retain the right to choose whether to receive the genetic therapy at the hands of the homosexual. After all, it will be about friends and partners that you may abandon.
    Most of the scientific respondents do not refer to homosexuality as a disease. point.
    Good signature and light fasting.
    Sabdarmish Yehuda

  7. Still and despite all the things you mentioned, a person is capable and obliged to heal himself.
    And just like there are the people who even cured themselves of cancer by sheer force of will and trust - true.
    This is how the desire to overcome that damaged genome becomes will.
    All the rest are the product of social laziness and a deep and liberating lack of awareness.

    This is my firm opinion.

  8. Homosexuality is genetic and it is a scientific fact, therefore; No matter how hard it is to accept the fact and try to distort it with your unnecessary opinions, it is necessary to accept a fact as a mature person who is ready to accept the truth.

    Another proof that the cause is natural/genetic is that at the moment of penetration in males (rectum), the hemorrhoids located at the opening of the rectum (anus) prepare the male's posterior sexual system for penile penetration, and therefore in most cases, the stool does not encounter the penetrating penis.** (The digestive system causes the stool to move backwards by the movement of the muscles backwards and this after penetration - taking into account slow penetration, and not fast penetration which does not allow the process to be carried out properly, the same as with straight men).

    As we know, the hemorrhoids are in the shape of the anvil like there is at the opening of the tube from which the food is swallowed - the anvil creates a preparation for the continuation of the tube so that there is swallowing of food without difficulties and choking.
    The reason why we usually choke is that the food does not always touch the umbilical cord or the food is not chewed properly and therefore, the penetration of the food causes choking. Likewise for hemorrhoids located at the opening of the rectum.

    Besides, during the births that the mother has, the level of testosterone (the male hormone) decreases and therefore creates an attraction to men.

    It must be remembered that homosexuality is not a sexual orientation, but a natural choice. (If it happened then there is no going back).

    Just as every gene has the ability to express itself unexpectedly (for example; cancer) "the genome is like a ticking time bomb" the gene responsible for homosexuality also has this possibility: the gene can be expressed after a person marries a woman, a person who wakes up in the morning and discovers a sexual attraction he had for women transposed to a sexual attraction for men. And some are even born with the attraction.

    It must be remembered that we are human beings, and the world we live in is full of a multitude of genetic, physical, etc. possibilities.
    If we find a reason for any phenomenon, it is possible that the above phenomenon operates in several other possibilities and not necessarily in one possibility for the phenomenon found (for example: the parallel between the phenomena of "the human genome as a ticking bomb", to explain phenomena such as homosexuality, pedophilia, achromatophilia (attraction to amputees), xeophilia Etc. etc'.

  9. Homespians=Atlantic brain=cold brain=snake brain.
    All the accompanying are metastases then to the rule reflected in the cerebral vertices of today and the excellent aspects
    in this article.

    Hugin: For the sake of your daughters in the rabbi.

  10. Jubilee in Scotland:
    In general, your thought seems correct to me, but let's think one step further.
    The researchers found that there are more cases of homosexuality in the mother's family.
    All in all, what the researchers described is more or less a private case of the idea you brought up, but exactly the private case that this figure brings into account (when instead of a meeting between two recessive alleles, there is a meeting between a recessive allele and "nothing").
    It is true that the way you presented things indicates that there are probably more options.

  11. Before me is the model of sickle cell anemia:
    The gene for sickle cell anemia is recessive, meaning that in order for the disease to manifest, both alleles need to encode the negative trait. On the other hand, if neither of the two alleles encodes sickle cell disease, the subject will die from another disease (malaria). It follows that the prevalence of the gene for one disease does not decrease as long as the other disease threatens.
    And in the context of homosexuality: I imagine that there is a system of several genes or alleles whose composition determines the sexual orientation. Whoever carries them all will be gay. He who does not carry anyone, will be straight. But in those who only carry some of them, useful qualities such as good intuition, artistic ability, and the like will be found.

  12. Hammer blows to the head are negative conditioning. Learn some psychology before you write.

  13. Mr. "LeMichael":
    First of all, I hope that's not your name.
    Besides - I read a lot about the conditions and they have nothing to do with your words.
    After all, the conditions are created, according to you, by causing pleasure - but what causes pleasure?
    Can you imagine learning to enjoy hammer blows to the head?
    There are probably situations where the sexual orientation is affected by the circumstances (according to the stories, being imprisoned in a prison is such a situation) but in general this is simply not true.

  14. Sexual attraction is not only genetic but also learned as a result of experiences.
    Read a bit about the conditions. Positive conditioning to speak what gives you pleasure.

  15. apology:
    When I quote from Wikipedia - I always use the English version.
    I know this is a bit burdensome for some readers but this is the only way to direct them to reliable information.
    The Hebrew version of Wikipedia is simply beyond criticism.

  16. Eyal:
    You are making a gross mistake.
    Sexual attraction is not learned. She is native. I know - at least for myself - that the possibility of having sex with a man never occurred to me.
    I belong to a generation in whose childhood conversations about sex were not common and no one ever prepared me for the fact that I would ever be sexually attracted to someone or something. It just came as a (pleasant) surprise and it was aimed in a very clear direction.
    When I learned that there were homosexuals, I was quite shocked because I did not understand how a person could feel this way and I emphasize - it is not that I had any criticism of such a person - I simply did not understand because in any introspective experience I could not detect even a hint of this type of attraction in myself.
    A lot of people I talked to experienced the issue in a similar way and later, when I had the chance to talk with gay men, it became clear to me that they had a similar process and the only difference was that their attraction was aimed at men and not women.
    Studies that have been done have raised a lot of doubt in relation to the question of whether there are even people who are attracted to both sexes.
    There is no doubt that there are people who behave this way, but the reason is probably an unwillingness to admit homosexuality.
    In the aforementioned studies, they used devices to test the sexual arousal that is created in people who claimed to be bisexual when they are shown pictures of men and women, and a reaction to only one of the sexes was always detected.

    The idea of ​​applying residual selection in this context seems to me far-fetched for many reasons and I will list some of them:
    Homosexuality also exists in animals that do not care for their offspring at all.
    In humans, most homosexuals tend to distance themselves from their families who do not show tolerance towards the phenomenon.
    In heterozygous organisms where inbreeding is not common, having one's own offspring conserves genes more effectively than protecting one's sibling's offspring (see )

    Ami Bachar:
    In section 3 of your response, you referred to reduced fertility in a different way than what the poet intended.
    The intention in the article is to reduce fertility as a result of homosexuality and not as a result of poor sperm quality.

  17. Yes, yes – Kin.
    I was eating and only had one hand to type. I didn't know that Keen Selection is a membrane that is Hebrew in Hebrew. Beautiful. thanks for the correction.

    Greetings friends,
    The one to whom his brother's blood cries out from the ground

  18. Larry Seter,
    What you describe is known as "Khin Selection". This explains many social phenomena and among other things the existence of women far beyond the reproductive age. Women are fertile for about a third of their lifetime (ages 15-45). One of the reasons suggested as an advantage is helping raise the grandchildren and great-grandchildren, as well as passing on knowledge and life wisdom acquired over many years to the children and their descendants.

  19. Interesting and sounds logical - the same set of genes that causes homosexuality increases fertility in women, therefore the rate of homosexuals is maintained, even though their reproduction is less.
    Several years ago I wrote an article in this journal that asks the same question but gives a different answer - the homosexuals helped in the care of their brothers (the name includes brothers and sisters) who carried genes for homosexuality and therefore their proportion in the population remained. I found this idea in books from about thirty years ago. This idea is of course based on insight and not on genetic or anthropological research.

  20. As a homosexual, I do not have the ability, like the other researchers, to point out with certainty the source and reason for this phenomenon. But one thing is known in the gay population, the tendency is not acquired nor does it arise from choice. The tendency seems natural and normal as if it were the straight path. Whether a person suppresses the fact or decides to accept it, the tendency remains the same.

  21. The tendencies and behaviors are related to genetic memory (secrets of ancient ages).

    The inclinations can be adjusted by consecration to the spirit, which is-is-is.
    After the end of the general repair and rehabilitation (at the end of the human cycle) the right balance will be found again.
    This study is important for general insights.

  22. Because it is about many details, according to the best of my knowledge. I tend to stick to the claim that humans are bisexual and homosexuality not only has a genetic component but also a preference.

  23. It is impossible to ignore dozens of studies that indicate that homosexuality is genetic.
    There may be individuals who want to try and know what it's like, but this does not make them completely homosexual, even after the experience.

  24. I think it's nonsense in the juice. Homosexuality is a sexual preference. There are a lot of people who try because they want to know what it's like or they are attracted. I think we are all two.

  25. very interesting.
    1) I'm not sure that homosexuality is only found in a few percentages of the population.
    2) If the same gene on the X chromosome causes excessive attraction to men, in both men and women, then it is likely that the percentage of lesbians in a gay family will be lower than in the rest of the population. This can be tested and it can strengthen the hypothesis.
    3) I find it difficult (perhaps difficult is not the right word here, but still) to accept the issue of reduced fertility caused by the gene that "encourages" homosexuality in men, since as humans we have good control over the times of our intercourse and are aware of pregnancy situations and the like - the less in the living world. Therefore, even a man whose fertility is less - although not acutely, will be able to impregnate a fertile woman after some attempts. It's not as simple as I present it, but when someone wants to get his wife pregnant and has the right equipment and the right desire (again, without acute harm to fertility) then this is much more possible than it is in the living world, where there is no choice and intelligent planning.

    Greetings friends,
    Ami Bachar

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