There is a widespread belief that one chooses to be a homosexual, and that people can successfully overcome such feelings.

On the other hand, some scientific studies have shown that finger length may be linked with sexuality:

It has long been suspected that high levels of androgenic steroids in the uterine environment have a musculizing effect on the fetus.

Furthermore, several psychiatric organizations claim it is not a choice, but disagree on whether it is completely innate, affected by early childhood, or whether we really have any clue at all!

So, as far as we know now, is homosexuality a matter of choice, nature, or nuture?

  • 3
    Which psychiatric organisations disagree on the cause?
    – Prometheus
    Jul 10 '17 at 1:25
  • I didn't choose to be straight, I simply am. Why would it be any more of a choice for a homosexual than for a heterosexual? The only ones that can choose are bisexuals. Nov 8 '17 at 4:41

To be clear, science has thus far failed to produce reproducible experimental evidence demonstrating a statistically significant genetic predisposition to any sexuality or a lack of one. There are only theories, no consensus.

This is part of a much larger problem dubbed "Nature vs. Nurture" that makes it extremely difficult to tell whether a great number of human characteristics (especially psychological) have a genetic predisposition or a purely a result of environmental parameters.

Some scientists have searched for a direct genetic cause of same-sex attraction—a gene or chromosome that actually determines sexual orientation. (Friedman and Downey, p. 149) Some studies hint at a biological component, but have not proven that same-sex attraction is an inborn or biologically-determined characteristic. If you read the reports published by the researchers, you find that they admit their current findings are not conclusive and simply hint at what some of the causes may be. Furthermore, these studies have not been able to be replicated. [1]

[1] Biological Causes of Same-sex Attraction, - A compilation of published Twin Studies, Brain Studies, Chromosome studies, Hormone Studies, and Psychiatric dissertations on Psychiatry.

How a particular sexual orientation develops in any individual is not well understood by scientists. Various theories provide different explanations for what determines a person's sexual orientation, including genetic and biological factors and life experiences during early childhood. Despite much research there is no proven explanation of how sexual orientation is determined. However, many scientists share the view that for most people sexual orientation is shaped during the first few years of life through complex interactions of genetic, biological, psychological and social factors.

Despite what some people claim, there is no evidence that society's greater acceptance of homosexuality results in more people having a homosexual sexual orientation. The greater numbers of people identifying as homosexual are a result of fewer people fighting their homosexual feelings while attempting to live heterosexual lives. [2]

[2] Australian Psychological Society, Psychology and Behavioural Sciences Collection database.

Although previous studies have suggested that sexual orientation is influenced by familial factors, which may be partly genetic, these studies have relied on unrepresentative and potentially biased samples. The authors attempted to estimate the role of genetic and environmental factors in the determination of sexual orientation in a more representative sample. [This study suggests that] familial factors, which are at least partly genetic, influence sexual orientation. The results of these analyses should be interpreted in the context of low statistical power and the use of a single item to assess the complex phenotype of sexual orientation. [3]

[3] Kenneth S. Kendler, M.D. et al. Sexual Orientation in a U.S. National Sample of Twin and Nontwin Sibling Pairs. Am J Psychiatry 157:1843-1846, November 2000.

  • 3
    How does this account for the finger-length ratio results then? As far as I knew these are highly statistically significant which strongly hints at a genetic component. (Although early development through environmental factors could probably have a similar result). Oct 30 '11 at 12:11
  • 7
    There is a statistical reason why definitive results are hard. The question is to what extent genetic predispositions can be modified by choice or environment. Some twin studies show that many "genetic" tendencies are overcome in twins raised together because of the competing pressure of individuals to be different (twins raised apart are more likely to be similar). This suggests there is sufficient plasticity in human nature for underlying genetic traits to be hard to identify in many circumstances.
    – matt_black
    Jan 8 '12 at 17:51
  • 1
    a current article on potential genetic basis for being homosexual, newseveryday.com/articles/28318/20151014/…
    – Himarm
    Oct 14 '15 at 16:51
  • Note that there have been some reasonably well-informed conjectures that homosexuality is somehow guided by the womb environment -- kind of in-between nature and nurture. Nov 6 '17 at 12:54
  • 4
    In scientific contexts, "theory" can generally be understood to mean "evidence-based consensus" such as in "the theory of gravity." You may want to use "speculation" or "hypotheses."
    – Tashus
    Nov 8 '17 at 21:51

Here is a good breakdown from a grad student on twin studies. However, the key thing to note reading through it is the re-iterated theme that most research to date has not been of a sufficient sample sizes to be able to claim to represent homosexuality in general.

How we define "homosexuality" is also very much up in the air, particularly with prison populations. When do two inmates having sex count as homosexual?

As far as we know, from a truly skeptic viewpoint, we just don't know yet what "causes" homosexuality.

I will add, as an aside, that this is insanely hard to research. 95% of all pages I get are strongly activist for or against.

  • 8
    As for definition, I really don't think having sex should be a part of it. In that case, I could have sex with a guy right now, just for the sake of this discussion, and that'd prove that it isn't innate, because I chose to temporarily become homosexual just to prove a point. I really think that attraction should be the interesting metric. That may or may not still leave prison populations in the grey zone, I'm not well read on the particularities of prison sex. Mar 10 '11 at 15:53
  • 3
    @David - I don't disagree with your definition. The point I was trying to make was that there is not a universally agreed upon, easily measured, definition used for research. That makes it even harder to aggregate studies because they don't all measure the same thing. The definition of "homosexual" could be a long discussion in and of itself :) Mar 10 '11 at 15:58
  • 3
    @Adam -- In science decade(s) old isn't a bad thing. A decade means there has been time to review and repeat studies. Time enough for real science, not just rubber stamp "science is good" consensus. Apr 10 '11 at 14:56
  • 12
    I'm sorry but this is NOT a good answer. It is not definitive and it makes no attempt to backup its main statement with any verifiable sources. It reads like the authors point of view, with a disclaimer. Surely this is a perfect example of a pseudo answer? Apr 16 '11 at 2:49
  • 7
    From the answer alone, nobody knows what the study says. Shouldn't you give a short abstract about the results? Jan 8 '12 at 15:03

There is strong evidence to indicate that in some (many?) cases, the cause can be developmental, i.e. a result of various effects while in the womb.

To quote from Wikipedia to summarize the theory:

The hormonal theory of sexuality holds that, just as exposure to certain hormones plays a role in fetal sex differentiation, such exposure also influences the sexual orientation that emerges later in the adult. Fetal hormones may be seen as the primary determiner of adult sexual orientation, or a co-factor with genes and/or environmental and social conditions.

A BBC Article from 2006 reports on a study published in the journal of the Proceedings of the National Academy of Sciences.

"These results support a prenatal origin to sexual orientation development in men."

He suggests the effect is probably the result of a "maternal memory" in the womb for male births.

A woman's body may see a male foetus as "foreign", he says, prompting an immune reaction which may grow progressively stronger with each male child.

The antibodies created may affect the developing male brain.

A 2010 paper by Dutch researchers seems to advocate that homosexuality is developmental rather than enviromental or genetic.

The fetal brain develops during the intrauterine period in the male direction through a direct action of testosterone on the developing nerve cells, or in the female direction through the absence of this hormone surge. In this way, our gender identity (the conviction of belonging to the male or female gender) and sexual orientation are programmed or organized into our brain structures when we are still in the womb. However, since sexual differentiation of the genitals takes place in the first two months of pregnancy and sexual differentiation of the brain starts in the second half of pregnancy, these two processes can be influenced independently, which may result in extreme cases in trans-sexuality. This also means that in the event of ambiguous sex at birth, the degree of masculinization of the genitals may not reflect the degree of masculinization of the brain. There is no indication that social environment after birth has an effect on gender identity or sexual orientation.

I can't access the full text of the paper so I don't know from what basis they draw their conclusions. However the paper is cited by a few reputable sources and was peer reviewed.

There is evidence of a very strong correlation between finger lengths and sexual orientations. To quote from a BBC article paraphrasing a 2007 study:

We can be pretty sure from a large number of human and animal studies that digit ratios are affected by prenatal testosterone exposure. So this result suggests a link between the hormones a baby is exposed to in the womb and their sexual orientation in adulthood,"

While we don't know the full range of factors that can cause or contribute to determining a persons sexual orientation, there is certainly good evidence to indicate that prenatal development and foetal hormones play a key part in many or perhaps even most cases.

Is homosexuality (meaning an instructive same-sex sexual attraction) always or generally innate? We don't know. Can homosexuality be innate? Almost definitely.

Other related studies and areas of research:

A 1978 study which has been widely cited since found that homosexual men tend to have higher levels of testosterone than heterosexual men.

Homosexuality in males is often linked to fraternal birth order, with the theory supposing that there is a maternal memory of sorts which builds up an immunity to a male feotus and the response can lead to homosexuality.

The Wikipedia page on Prenatal hormones and sexual orientation has a good summary (although poorly formatted with links to many relevant studies.

  • 2
    I intend to update this to note the differences in hypermasculinity and hypomasculinity, what we know about female homosexuality and how it differs from male homosexuality and the evidence for genetic and/or environmental causes. Mar 1 '12 at 5:56

A homosexual person does not choose to have the trait of homosexuality. However, the person is more likely than others to choose homosexual behavior due to having that trait.

Most of the controversy surrounding this topic can be attributed to misunderstandings in terminology. This is because when someone mentions homosexuality, they could actually be referring to one or both of two very distinct things.

The first thing they could be referring to is a homosexual person. A homosexual is defined as, "a person who is sexually attracted to people of their own sex." Sexual attraction is an inborn instinctual trait that affects whom we are drawn to and how we relate to them. As with many things in nature, sexual attraction is subject to genetic variance which is why people tend to have their own "types" and not everyone is attracted to the same traits in others. This is why (similar to being left-handed) homosexuality occurs in a small percentage of people regardless of their race or culture. However, it's not a simple binary (yes/no, on/off, true/false) system. Perceived gender is only one of many things that determines how one person falls on the spectrum of attractiveness to another person. For some, gender bears little or no influence on their attraction at all (see bisexuality).

The second thing they could be referring to is homosexual behavior or those who participate in it. Homosexual behavior is typically seen as any sexual act involving members of the same gender. Unlike sexual attraction, sexual behavior (or any behavior) is subject to reasoning (choice), which can be highly influenced by culture, experience and environment. Being sexually attracted to a person is not a requirement for engaging in sexual behavior with them, it just makes it much more likely to occur. This explains why a person who identifies as "straight" might participate in homosexual behavior in prison. Not because their attractions have dramatically changed, but rather because their desire to perform the act (also instinctual) combined with their environment may lower the bar for whom they find acceptable. The same can be said for those who participate in either side of a prostitution agreement.

There are a lot of parallels that can be drawn between homosexuality today and the time when being left-handed was controversial. During that time, children were punished for using their left hand and forced to learn using their right one. It's possible for a left-handed person to pretend being right-handed their entire life by choosing to avoid left-handed behavior and actions. However, regardless of how proficient they get with their right hand, it won't feel natural to them. A lot of emotional damage can be caused along the way by the culture that rejects them for who they are or feelings they can't control.

  • 4
    Welcome to Skeptics! Please provide more references to support your claims. The references you include only cover a small proportion of your claims. (e.g. you conclude that twins both being sexually attracted to blondes implies that their homosexual "traits" will be similarly inherited. This needs a better reference.)
    – Oddthinking
    Nov 23 '12 at 6:37
  • 2
    Unfortunately, as a new user, I was only allowed to include up to two links in my answer. The two chosen are what I believe to be the most appropriate ones based on the question and cover the most relevant points made. Also, I made no references to twins, blondes or inheritance, so I'm not sure if that was intended for my answer or another one.
    – user10407
    Nov 23 '12 at 7:33
  • 1
    Hi, you can still add references in text (by just posting the url). This site is community edited and people with more rep can change the urls into full links.
    – Sklivvz
    Nov 23 '12 at 7:58
  • Ah, sorry to hear you were caught by that restriction. It particularly targets new users, which is unfortunate. Sorry for being unclear about the twins and blondes. I was characterising the results of the study you did cite as evidence that "sexual attraction is subject to genetic variance". That study didn't look at gender preference. (Hmmm, I just realised "gender preference" is a phrase that begs the question of whether it is a preference or not.)
    – Oddthinking
    Nov 23 '12 at 9:50
  • 1
    I was wondering if you have any evidence on the left/right handed being an immutable thing? A lot of people seem to be righted handed for some things and left for others. I know after a hand injury I just became left handed for some activities. I always thought it was just practice/muscle memory/strength. not anything innate.
    – Jonathon
    Apr 24 '15 at 19:05

This question simply boils down to the "nurture" vs "nature" argument. You are asking if it is "innate" (aka part of your "nature") or something that is externally created ("nurtured").

Given what we know, homosexuality is almost certainly a matter of nature -- as there has never been any successfully proven method for changing someone's sexuality. Given the number of people who commit suicide because of, or otherwise struggle with, being gay, there's no shortage of a market for such an ability.

For example, the Mormon Church used to recommend that its members who have gay feelings to get married as quickly as possible, and try to forget about their urges. At times they have even been known to resort to electroshock therapy when trying to "cure" people of homosexuality. To my knowledge, they do not have a good success rate.

Of course, you may argue that there is a way to change someone's sexuality, we just haven't discovered it yet.

With that in mind, if we look outside of the social constructs of man to the world nature, we have found homosexuality in nearly 1,500 species (so far). From fish, to insects, to penguins, to lions. And as humans are simply animals too, there's no reason not to think that what we see occurring in nature, doesn't occur within us. In fact, it would be very usual if it didn't.

So that often leaves people wondering: WHY? Why does nature still create gay animals? Shouldn't they have died off if their genes aren't being passed on into future generations? One of the theories as to why nature makes a certain percentage of humans gay is because they might help to protect and raise the young of a given tribe. I.e. Without offspring of their own to look after, they are perfect uncles to help ensure the future of their group's genes.

Finally, it's worth noting that Kinsey saw that sexuality is prone to change throughout life. The few people who consider themselves "ex-gay" (should they exist and are being honest with themselves) may simply be those who would have naturally changed their sexuality anyway.

One thing that everyone who has studied the subject seems to agree upon is that it's not a conscious decision. So even if something in childhood does affect sexuality later in life (as you speculate in your question), it is essentially "innate" once someone's sexuality has developed.

Or, as the popular YouTube video asks: When did you choose to be straight?

(An aside: Because of its occurrence in nature, homosexuality is, by definition, completely "natural" -- i.e. It "exists in nature; not made or caused by humankind".)

  • 1
    -1 Talking about animals doesn't really answer the question. Jun 15 '11 at 16:46
  • 10
    Human beings ARE animals. So why would we be different? It's entirely relevant, unless you don't believe in evolution. Jun 18 '11 at 15:20
  • 4
    -1 because the question isn't disputing that non-human animals have preferences; these preferences can be genetic or environmental or incidental; they can be strong or mild; they can be reinforced or discouraged though various conditioning methods with various long- and short-term consequences. The question is which kind of preference is homosexuality?, not do animals have varied sexual preferences?
    – user792
    Jan 8 '12 at 18:34
  • 1
    I don't think "preference" is synonymous with "choice." For one thing, I don't think you're working from any reasonable definition of "choice." Second, for example, the human preference for eating sugar, and likewise not eating feces, is most definitely innate and genetic - nonetheless it's still a preference, a liking for one thing over another. Also I never said "encouraged" so I don't know what you're quoting.
    – user792
    Jan 9 '12 at 16:13
  • 1
    On a more serious note, animal (other than human) homosexuality is not a consensus between researchers. They certainly have sexual activities sometime with the same sex, but that does not mean that they are explicitly homosexual.
    – Zonata
    Oct 11 '12 at 2:04

Since homosexuality is seen in many animals, not just humans I'd say it's innate, natural and doesn't factor in choice at all.

In many ancient cultures (pre Judeo-Christian) homosexuality was reportedly very common.

For example in ancient Rome and Greece

  • 9
    'unnatrual' is a bogus term, I'd refrain from using it. It isn't tantamount to anything more than 'I personally don't approve of this, and I'm going to say that nature is on my side in that regard'. The line between natural and unnatural could never be anything but completely arbitrary, because everything phenomenon that exists in this world is the very remote end product of a natural process. Mar 10 '11 at 15:13
  • 5
    @JinX: That's extremely confrontational and offensive, and if I could vote you down again I would. I support the rights of homosexuality, but this answer is more of an expression of your issues with organized religion than any useful commentary on the subject matter at hand. Mar 10 '11 at 15:15
  • 3
    As for the downvotes, I guess they're mainly because your answer turned into some weird assertions about the nature of catholic pedophiles. I don't think you have to be catholic to think that that's completely off topic in a question about homosexuality. Mar 10 '11 at 15:16
  • 4
    @JinX: your distinction between what happens in nature and culture is arbitrary. Culture is natural. We exist, in nature. What we do happens in nature. Mar 10 '11 at 15:34
  • 9
    Many animals can breathe underwater. Would that mean it is innate and natural for humans to do so? To show that some group of animals has a characteristic in no way provides evidence that humans have an innate one as well
    – jjj
    Mar 11 '11 at 22:12

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