8 major studies of identital twins prove homosexuality Is NOT genetic

From OrthodoxyToday:

Identical Twin Studies Prove Homosexuality is Not Genetic

Eight major studies of identical twins in Australia, the U.S., and Scandinavia during the last two decades all arrive at the same conclusion: gays were not born that way.
“At best genetics is a minor factor,” says Dr. Neil Whitehead, PhD. Whitehead worked for the New Zealand government as a scientific researcher for 24 years, then spent four years working for the United Nations and International Atomic Energy Agency. Most recently, he serves as a consultant to Japanese universities about the effects of radiation exposure. His PhD is in biochemistry and statistics.
Identical twins have the same genes or DNA. They are nurtured in equal prenatal conditions. If homosexuality is caused by genetics or prenatal conditions and one twin is gay, the co-twin should also be gay.
“Because they have identical DNA, it ought to be 100%,” Dr. Whitehead notes. But the studies reveal something else. “If an identical twin has same-sex attraction the chances the co-twin has it are only about 11% for men and 14% for women.”
Because identical twins are always genetically identical, homosexuality cannot be genetically dictated. “No-one is born gay,” he notes. “The predominant things that create homosexuality in one identical twin and not in the other have to be post-birth factors.”


Still, many misconceptions persist in the popular culture. Namely, that homosexuality is genetic – so hard-wired into one’s identity that it can’t be changed. “The academics who work in the field are not happy with the portrayals by the media on the subject,” Dr. Whitehead notes. “But they prefer to stick with their academic research and not get involved in the activist side.”

Human beings are not slaves to their appetites and impulses, as animals are.  We make choices.  Even those who have the affliction of a strong same-sex attraction can make choices to live a virtuous life, just as those who are undoubtedly heterosexual have to make choices.

About Fr. John Zuhlsdorf

Fr. Z is the guy who runs this blog. o{]:¬)
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  1. msc says:

    However, if homosexuality is the result of powerful formative influences during a person’s infancy, it might as well be genetic. So much of our character is formed during our early years, and much of that will not change during a person’s life.
    But it is still good to have further evidence against the genetic argument. I would need to read the study to see how many of these twins were raised in virtually identical circumstances and in virtually identical ways. I do wonder, however, how one explains apparent committed homosexual behaviour among animals. Some birds and mammals do appear to form bonds only with animals of the same sex. That has to be genetic. And if it is genetic in them, then the same genetic forces could affect humans.

  2. Supertradmum says:

    All of us have afflictions of some sort. We can choose to follow the Cross, or give in to the passions. I am so glad you shared this, Father, and I would hope that more research in America and Europe would follow up on this truth.

  3. Moral_Hazard says:

    Does anyone have a link to these studies or an article on these studies that does not come from a religious or partisan media outlet?

  4. Someone please be the Garrigue says:

    Follow the HT link, and there’s a link to the source:

  5. mburn16 says:

    The topic of genetic influence of various conditions is a fascinating one. Even for a condition like Diabetes, there is no direct correlation with being a twin. When one twin develops that condition, his or her sibling is only likely to do so around half the time.

    I suspect homosexual urges (which do also occur in animals) are rooted in one of two things: either a spontaneous gene mutation, or a chemical issue in the brain during gestation (which would not inherently affect both twins).

  6. kekeak2008 says:

    I am a twin myself, and my brother is gay. The only difference in our children was that we went to different schools growing up (long story). I always dispute those who claim it’s genetic. One may have a strong inclination towards it, but that hardly qualifies as a “genetic predisposition.” And as Fr. Z mentions, we aren’t slaves to our desires or human inclinations. We can make a choice. The Lord has granted us free will.

    Further studies will have to be performed before the mainstream accepts this premise (if they ever do).

  7. TraditionalCatholicGirl says:

    I’ve been telling this to my friends and family (who all support, or are at least indifferent to same-sex “marriage” and homosexuality), and I have been laughed off. Based off of pure common sense, any person can come to this same conclusion as these studies have. Yet we are mocked and called bigots for exercising our intelligence and concluding in this manner.

    Isn’t it unscientific to eliminate one of the possible outcomes at the start before coming up with the final derived conclusion? That’s exactly what these activists are doing! And it doesn’t just apply to this issue: you could apply this same flawed logic to practically any disputed topic out there today.

    What a backwards, “tolerant” world we live in, where we would rather tell a sweet falsehood to make someone feel better about living in error, than to tell them a sometimes bitter tasting truth and correct them.

  8. JudicaMe says:

    I am in those numbers who, with the grace of God, struggle to live a virtuous life. I can tell you that it’s not easy. I fall, I try to get up, thanks to Fr. Z’s constant reminders to go to confession. My deepest fall was in 2013-2014 time period when I was involved with a guy in a more serious manner that I could not approach the Altar for Holy Communion. It was like a thorn in my flesh. Through Providence, the relationship did not work out and by the same providence I could go to confession with an FSSP priest. I did not know why I asked for a confession (most probably it’s Fr. Z frequent reminder) but I did. And I received Holy Communion after God knows how long.

    Anyway, Rev Father, this is my gratitude for your ministry here so that you know how much your work has born fruits in us, readers.

  9. Sonshine135 says:

    I have always believed that homosexuality being classified as genetic was a farce. If homosexuality is not genetic, does this not mean that the greater possibility that homosexuality is directly related to the environment in which a person grows up? Much of what I have read indicates that this is the case. I believe there is a strong correlation pointing to homosexuality being what it was originally classified: An obsessive compulsive disorder where the compulsion is ones own sex, and caused by one’s own environment. This is not much different from sexual addiction which would be classified as a compulsion towards one with the opposite sex.

    Our society acknowledges one as disordered (sexual addiction) while saying that the other (homosexuality) is normal. The evidence that homosexuality is normal has always been specious at best. Don’t expect the Orthodoxy Today article to be front page news anywhere in any case.

    Finally, knowing that a child’s social setting is a key factor, would governments do anything about allowing gay couples to raise kids? Unfortunately, I think that ship has already sailed. The next generation of homosexuals are already being raised.

  10. iPadre says:

    Glad you posted this. I lost the link a few days ago.

    I have a Courage group in my parish and they have been saying the same thing. Many studies have been done by the “gay” community have reaffirmed this.

  11. JARay says:

    I find this most interesting. The facts need to be widely disseminated.

  12. Dennis Martin says:

    A word of caution. I followed the link given up thread. It links to a book published by Dr. Whitehead (whose doctorate is in biochemistry), titled, My Genes Made Me Do It. Chapters can be downloaded as pdfs or the book can be purchased in various formats. The book is one section of a website devoted to scientific evidence that same-sex inclination is not hard-wired and can change.

    I assume that Dr. Whitehead has accurately summarized the 8 studies. But the link does not lead to the studies themselves, only to his summary. Anyone who cites this article from the Orthodox journal or cites directly to ch. 10 of Whitehead’s book, should be prepared for advocates of a genetic origin for same-sex attraction to dismiss it and Dr. Whitehead’s website as an untrustworthy summary of scientific studies by a biased, homophobic, summarizer. Please note, I am not saying Dr. Whitehead is homophobic or inaccurate. But he will be dismissed by many and you should be aware of that when you recommend this article or his book to others.

    Even if Dr. Whitehead’s summary of the 8 studies is accurate, as I assume it is, it will be discredited by those who are deeply, existentially committed, to the opposite conviction. And, as someone pointed out upthread, even though it would seem pretty clear that the origin of same-sex inclination is not genetic, it does also appear to have some powerful, largely unchosen socio-psychological roots, at least for many. It is that apparent fact that weighs heavily upon those who suffer from this affliction (some of whom would label my words here as also being homophobic; some day “suffer from same-sex affliction” will be criminalized as hate speech, indeed, in some ways it already is) and makes them eager to explain it as genetic.

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  14. everett says:

    One thing to mention is that, presuming as Dennis does, that the summary is accurate, it would seem likely that there is some genetic component, as the twin having a rate of 10-15% is significantly higher than the general population. However, this would be more along the lines of increased tendency, rather than deterministic. Most importantly, the genetic argument is irrelevant – even if it were 100% genetic, the sin is the act, not the attraction.

  15. Alsatian says:

    In order to distinguish genetic from environmental effects on behavior, the incidence of identical behavior between identical twins raised together must be compared to identical twins raised apart, fraternal twins raised together, full siblings, and unrelated individuals. A genetic effect is strongly suggested by similar rates of identical behavior in identical twins raised apart and identical twins raised together. Here, the summary provided does not give any sibling data. However, we do see that 11% of gay identical twins having a gay brother is approximately 5x the incidence of male homosexual identity within western populations (est. ~2%), implying that co-incidence of homosexuality among identical twins is much higher than predicted by mere chance. Moreover, the same stats that Dr. Whitehead cites to discredit the genetic hypothesis also discredit the environmental hypothesis – if one assumes an identical environment for identical twins raised together. We are left, then, with neither a genetic nor an environmental explanation for an inclination that is strongly perceived as innate by those who possess it. Still, we have a trait that is coinciding between identical twins at five times the expected rate. This could conceivably be explained by a genetic trait of low penetrance, or a trait determined by multiple genetic loci of moderate penetrance, where penetrance is stochastically determined. 100% coincidence would only be expected with a trait controlled by loci which all show 100% penetrance. This is rare for behavioral traits. The data as reported are still consistent with a genetic, not to mention a developmental, effect entirely outside the homosexual’s control.

  16. gramma10 says:

    Very controversial topic.
    I think though it may be rather simple. When someone chooses to do something morally wrong they must have a good reason why they can’t help it. Then they can justify their choice.

    Isn’t it the Garden of Eden, all over?

    It used to be clear—-what was right and wrong. Now everything is relative, yes?

    Seems to go back to unsound and untrue teaching and whatever feels good, do it!

    If we rationalize our choices then we can convince ourselves of the lie and it is easier to stay that way.

    Been the problem in the world since day one.

    Sooo as we know Christ is the answer. That is the truth but we cannot force anyone to believe anything they don’t want to.

    Guess we need to speak the truth in love and pray! Plus teach the faith and reflect the Son.
    What a mess we all are in! But Gid is in control.
    As the sign says “If God is your co pilot–swap seats”.

  17. Stephen Matthew says:

    Actually, it would be more accurate to say it isn’t strictly and exclusively genetic. There may be some genetic factor still involved, but it is more complicated than that. (There are in, addition the traditional ideas about nature/nurture arguments, the recently developing field of epigenetics, that studies issues of certain genes being activated by certain conditions while other genes remain dormant.)

    The interesting thing about twin studies, is sometimes twins don’t grow up together at all. Sometimes twins are separated at birth. These are the most useful twin studies, because it eliminates many non-genetic influences that are normally nearly identical for twin raised together. Comparing the outcomes for two such individuals, you find all sorts of interesting things that are genetic, that definitely are not genetic, and then a large third category of things that are not strictly and only genetic but likely have a genetic component. It seems that sexual orientation falls into that third category, of things that have some element of genetic predisposition, but is determined by some more complex set of influences.

    In any case, the answer seems to be in some combination of genetics, epigenetics, environment, circumstances, and personal development.

    However, if it is genetic or not is ultimately irrelevant to the moral question, and I think it highly foolish for many of the defenders of traditional sexual morality to spend such a great deal of time on debating what is a scientific question that does not determine the moral question. By arguing on this ground it appears, to observers, to implicitly concedes that if it is genetic then it is moral, and that is utter rubbish.

  18. The Masked Chicken says:

    I don’t like junk science. This is excellent 1980’s research, but as a research scientist, an identical twin, and as as someone who has studied the twinning phenomenon, let me start by disabusing people of the notion that having identical DNA makes identical twins biologically phenotypically identical. This cannot be guaranteed except at the moment of twinning, when the parent cell divides in two. The likelihood of identical phenotypicality remains high for a substantial period during gestation, but is not identically 100%. After birth, all bets are off. The reason is because of a phenomenon we are only beginning to understand: epigenetic modification of DNA expression. Genes express proteins, when activated, but we are finding out that environmental stressors can activate certain genes that might not, otherwise, be activated, thus, altering the biochemical environment. It is like having two identical cars, but you accidentally spill some gasoline in one of them. It runs. The other one doesn’t. Here is a link to an NIH white paper about the epigenetic variations in twins.


    Thus, it is possible for one twin to express a phenotype while the other doesn’t because of some environmental stressor. While the underlying DNA sequence is not changed, the gene expression has changed. To not call this genetic, or more precisely, epigenetic, is to revert to 1980’s biology.

    Without actually assaying the DNA of the twins to look for subtle genetic (or epigenetic) variations, any study done on a purely observational basis is cargo cult science. There is no baseline for comparison established between the two twins. So, the question of whether or not homosexuality has a biological epigenetic component has not been answered by these studies. Homosexuality is a subtle thing and one would expect that subtle alterations in gene expression might have an effect, unless the twins are reared truly identically, which, of course, would be needed to prove no epigenetic influence or even mutational influence that is not environmentally-mediated, but random.

    So, this meta-study proves nothing, except that one can define the word, “genetic,” in such a tightly unrealistic way so as to arrive at a conclusion. This is the definition of cargo cult science. Sorry, I don’t accept that they have proven anything by these studies except their lack of rigor.

    The Chicken

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  20. Folks, I have to close comments on this. I have too much on my plate today to monitor this one and the other things I have to keep track of… and ready a Pontifical Mass.

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