The Parasite Hypothesis For Male Homosexuality

“Saccharine Psycho-Virus”

This article is available as both a webpage and a .pdf file download.

1. Introduction

Many authors have previously suggested that pathogens or parasites may be a possible cause of homosexuality, including Gregory Cochran in 20001, Steve Sailer in 20032, Peter Frost in 20093, Brittonic Memetics in 2023, and likely many others that I am unaware of. Additionally, the pseudonymous youtube essayist “Blithering Genius” has elaborated on the hypothesis perhaps most eloquently in his 2016 video, “Sacculina”, and his 2023 essay “Parasites, Emotions, and Identity”. This theory became viral on September 20, 2021, when an anonymous user on 4chan’s pol posted a hypothesis4, which became informally known as the “worm pill”.5 There is a cultural bias in the Modern West against viewing homosexuality as a disorder, so there isn’t that much research into its causes. This essay is a comprehensive, yet succinct look at the parasite hypothesis for male homosexuality, with regard to the implications it has for specifically. As of now, we are reserving judgment on other speculative effects of parasite infection, those being motivation to engage in other forms of abnormal sexual behavior: transsexualism, bestiality, etc.

Note that female homosexuality likely has different causes from male homosexuality. The evidence for the parasite hypothesis doesn’t fit as well for female homosexuality, we know that there are some causes of male homosexuality that don’t apply to female homosexuals, and female same-sex-attraction is more continuously distributed along the Kinsey scale compared to male same-sex-attraction. Some biologists have speculated that female homosexuality is a by-product of genetic selection. In any case, female homosexuality is not the focus of this essay.

2. Evidence In Favor Of The Parasite Hypothesis

There are known examples of similar phenomena that occur in the wild. A parasite called Sacculina infects a male crab by attaching to its genitals and giving it hormones to make it behave like a female crab. It then causes the male crab to nurse the Sacculina’s eggs. The parasite reproduces and the cycle continues. A more commonly known example is Toxoplasma Gondii. These parasites reproduce in the intestines of cats and lay eggs in the cat’s feces. They then spread to other intermediary hosts such as rodents. The parasite infects and modifies the behavior of rodents to make them attracted to cats, rather than fearful of them. The cat then eats the infected rodent, and Toxoplasma Gondii is able to reproduce again. These are well established examples of parasites exploiting another organism’s form for their own benefit.

All STDs are caused by parasites. Virtually every STD is orders of magnitude more prevalent among Men Who Have Sex with Men (MSM) than it is among the general population. We’re not claiming that there are known STDs that make people gay, but this does demonstrate that pathogens do spread better among homosexual men than other populations.

Furthermore, most people are disgusted by homosexual intercourse and sexual promiscuity. This instinct (commonly labeled “homophobia”) is part of the immune system, and is usually reserved towards disease and infection vectors that humans have been exposed to for millennia, such as decaying organisms, insects, arachnids, fecal matter, etc. This natural instinct is so strong that cultures and religions have evolved explicit values and policies against homosexuality (e.g. Islam and Christianity). Similar religious policies include the banning of certain kinds of food, or unsafe preparation methods to limit the spread of disease. In homosexuals, the disgust response towards homosexual intercourse is gone, despite the high risk of catching a multitude of diseases that reside in fecal matter and may be transmitted via anal sex. Additionally, homosexual men tend to be more sexually promiscuous relative to normal people. They tend to have sex more often and with far more partners. These facts are consistent with the parasite hypothesis because an intestinal parasite would be able to spread itself to more hosts if its current hosts engage in frequent anal sex. These behavior patterns are also consistent with the disgust response in homosexuals being suppressed by something. It could be that this specific yet simple behavioral effect happens to be good at propagating pathogens.

Pedophilia is another behavior that is more common among the homosexual population than the heterosexual population. “A study in the Journal of Sex Research found that although heterosexuals outnumber homosexuals by a ratio of at least 20 to 1, homosexual pedophiles commit about one-third of the total number of child sex offenses” (Dailey)6. This disparity fits the hypothesis, because it would be advantageous for parasites to infect their hosts as early as possible if they rely on psychologically modifying their hosts. The younger the host, the more plastic the brain will be. Parasites are thus motivated to cause their hosts to engage in sexual intercourse with young children and younger men.

Above all, the primary evidence for the parasite hypothesis is homosexuality itself. Over 75% of homosexual couples don’t raise any children at all. Since homosexuals don’t reproduce nearly as much as heterosexuals, the condition is unlikely to be hereditary. If it were, then it would select against itself and be an evolutionary dead end. Instead, the condition is present in more than 1% of the male human population. This implies that most cases of homosexuality are caused by environmental factors, not genes. It’s thus the prevalence of homosexuality that requires explanation. We have yet to find any precise causal pathway to explain homosexuality, so we should prioritize investigating theories that could explain a prevalent maladaptive behavioral pattern. If a reproducing machine is doing something other than reproducing, we should suspect the involvement of a parasite that has captured the machine.

3. Addressing Objections to the Parasite Hypothesis

We would have already noticed a gay germ if there was one.

On that basis, it’s somewhat unlikely to be a known pathogen. As far as I know, nobody is looking for a correlation between homosexuality and pathogens. I’ve never seen an epidemiological study of homosexuality (please contact me if there has been one). it could also be that the pathogen is something that most people have evolved resistance against.

To clarify, we’re not claiming that a known STD is the cause. The hypothesis is that an unknown pathogen is the cause. It took a long time to connect ulcers to bacteria. In general, it can take a long time to identify a pathogen, even if you suspect one. It will be interesting if we ever do.

Lastly, if the argument is that the germ hypothesis is false because we haven’t found the germ, then that would apply to every hypothesis since they have all failed to have found a specific causal mechanism yet.

But if the parasite transmits itself through anal intercourse, then why would it limit its host population to men? Women can receive anal intercourse too.

Women may be another vector of transmission, but male on male sex is still a more efficient channel of transmission overall, compared to transmitting male to female or female to female. Males tend to higher sex drives and they have phalluses that make it easier for newly infected hosts to spread the parasite to other hosts via anal intercourse. Males thus require less modification than females for becoming viable hosts to parasites. The higher prevalence of STDs among MSM suggests that homosexual men would make better hosts for such a parasite to procreate and multiply.

If the hypothesis was valid, one should observe an increase in risk of becoming homosexual after an infection with a pathogen. Such a relationship is not observed.

Perhaps, but since we’re hypothesizing that male homosexuality may be caused by an unknown pathogen, we can’t analyze a correlation unless we identify the pathogen to begin with. Also, given that the development of sexuality occurs later in life, it’s possible that pubescent or prepubescent parasitic infections are the reason why we don’t observe this relationship.

Homosexuals who are attracted to minors are typically interested in teenagers, not prepubescent children.

This does not refute the parasite hypothesis because the adolescent brain is still developing and is more pliable than an adult one. Adolescent brains are also within the typical age range for when humans start to develop sexual attraction, so teenagers may have the most optimal brains for parasitic modification and re-wiring among all other potential hosts.

Are there ways for the parasite(s) to spread, besides anal intercourse?

If there is a parasite, it’s possible or even likely that it can be transmitted in other ways besides anal sex, but more research would be needed to determine what other infection vectors may be viable. Given the evidence, it’s reasonable to assume that homosexuality is ancient, widespread and maladaptive, but each of these assumptions can be disputed.

4. Other Causes of Male Homosexuality

There are other documented and proposed causes of homosexuality, and there is a consensus that hormones are involved in sexuality. Homosexuality is known to be associated with abnormal prenatal hormone levels during crucial neurological development periods (Sheppard)7 and (Wilson)8. This may be a separate cause of male homosexuality, but if so, then it’s assuming that a key human reproductive function has been causing 2 to 5% of males to have significantly less offspring without it being selected out. No one claims that evolutionary theory alone suffices to explain everything about human behavior or disorders, but evolutionary theory constrains any such explanation. If a proposed mechanism assumes natural selection somehow stopped acting with respect to this trait for hundreds of generations, then it is probably false. The hormonal imbalance hypothesis also cherry-picks its own evidence, since it ignores research about how homeostasis is hard to knock out of equilibrium in key reproductive functions. The hormonal imbalance hypothesis is thus not a solid explanation for male homosexuality because its premises are not consistent with evolutionary theory or physiology.

It’s also possible that the hormonal imbalance hypothesis could be connected to the parasite hypothesis, since there are known parasites that control sexual development by secreting hormones (e.g. Sacculina), and also since people typically inherit their gut flora from their mothers during birth. Gut flora could affect the prenatal environment, the mother’s immune system, or hormones in the mother’s blood. If there is a connection between these two hypotheses, then the hormonal imbalance hypothesis would be consistent with evolutionary theory.

Another possible cause is having multiple older brothers, which can cause an immune response or an allergic reaction in the womb that turns male fetuses homosexual. The mechanism is thought to be a maternal immune response to male fetuses, whereby antibodies neutralize male Y-proteins thought to play a role in sexual differentiation during development.9 Fraternal birth order is thought to cause homosexuality in at least one-sixth of all homosexual men. But once again, this hypothesis also fails to explain why homosexuality has persisted without its causes being selected out of the gene pool, i.e. genetic factors that contribute to the immune response in the mother’s womb.

Since we know that there are multiple causes of male homosexuality, homosexuals could be separated into two groups if the hypothesis is true: 1. those who have been infected with parasites, and 2. those who have not. If a large fraction of homosexuals are not affected by the parasite, then future research could investigate the ratio of parasite-infected homosexuals who did pedophilia vs non-parasite-infected homosexuals who did pedophilia, and that could reveal more information about the strong correlation between homosexuality and pedophilia.

Lastly, the validity of the Gay Uncle Hypothesis depends on the validity of kin selection theory. While it is true that some homosexuals do adopt children, the 2010 US Census shows that about ~80% of children raised by homosexuals are the biological offspring of one of the homosexual partners, and homosexual men are far less likely to have biological children than homosexual women. Kin selection theory is also based on fallacious reasoning, so it should be rejected in favor of the phenocentric theory of biological purpose. Likewise, the “highly polygenic” hypothesis purports to explain why we haven’t found the specific genes, but it ignores that homosexuality is barely hereditary at all to begin with. That said, we can soundly reject both the Gay Uncle and Highly Polygenic Hypotheses since there is no sound reasoning to support either of them.

Some people may say that this hypothesis is too unlikely to have any possibility of being true, but given all the facts that we have stated about homosexuality and how humanity has been so unable to figure out all the factors and contributing causes to homosexuality, is this hypothesis really any more unlikely than other proposed explanations, especially given when they fail to explain why homosexuality is so unexpectedly common in the first place?

5. Final Thoughts

Most people presume that what we view as good or acceptable must be natural and normal. This general moralistic fallacy is the main reason why homosexuality is not considered a disorder in recent times. “Disorder” is a kind of value judgment, but with respect to an objective norm, such as biological function. The cultural view of homosexuality went from judging it as a “morally wrong” disorder in the DSM to “morally acceptable psychological disorder” to “natural, normal, and healthy”, and even to some extent “morally and personally good”. Nowadays, there is huge pushback to anyone pointing out the obvious fact that homosexuality is a biological disorder of some kind, because it’s perceived as saying “homosexuality is bad”. If the parasite hypothesis can be verified to be a true cause of male homosexuality, it would be a humiliating and terrifying blow to the LGBTQ+ movement that so much of its cultural activism and virtue-signaling was motivated by parasites.

It’s possible that drugs that purge intestinal parasites such as ivermectin (“horse de-wormer”) could be used to remove such parasites and give infected people another choice about how they continue to live their lives, should this hypothesis be true. There is anecdotal evidence that this has worked4, 10. We recognize that this is a very speculative and controversial hypothesis, but nonetheless, we recommend that the scientific community conduct more research to investigate the effects of parasite cleansers on homosexuality.10

© The Pragmatopian & Zero Contradictions 2022-2023. All rights reserved.

6. Other Sources

Bering, J. (2011 March 9). Natural homophobes? evolutionary psychology and Antigay Attitudes. Scientific American Blog Network. Retrieved February 11, 2022, from https://blogs.scientificamerican.com/bering-in-mind/natural-homophobes-evolutionary-psychology-and-antigay-attitudes/.

Cochran, G. (2013 November 6). Depths of madness. West Hunter. Retrieved February 11, 2022, from https://westhunt.wordpress.com/2012/02/16/depths-of-madness/.

Freund, K., & Watson, R. J. (1992). The proportions of heterosexual and homosexual pedophiles among sex offenders against children: an exploratory study. Journal of sex & marital therapy, 18(1), 34–43. https://doi.org/10.1080/00926239208404356.

Keystone, J. S., et al. (1980 September 20). “Intestinal Parasitic Infections in Homosexual Men: Prevalence, Symptoms and Factors in Transmission.” Canadian Medical Association Journal, vol. 123, no. 6, pp. 512–514, https://pubmed.ncbi.nlm.nih.gov/7437971/. Accessed 10 Aug. 2023.



Cochran, G.M., Ewald, P.W., & Cochran, K.D. (2000). Infectious causation of disease: an evolutionary perspective. Perspectives in Biology and Medicine, 43, 406-448. https://citeseerx.ist.psu.edu/viewdoc/download?doi=


Sailer, Steve. (2003 August 17). “Gay Gene Or Gay Germ?”. VDare. https://vdare.com/articles/gay-gene-or-gay-germ.


Frost, Peter. (2009 February 19). “Origins of male homosexuality: the germ theory”. Evo and Proud. https://evoandproud.blogspot.com/2009/02/origins-of-male-homosexuality-germ.html.


To be clear, we see no reason to suspect a worm specifically for the pathogen. We only suspect an unidentified pathogen of some type.


Bickerton, Sean T, and Timothy J Dailey. (2002 June 29). “Pedophilia and Homosexuality.” The Washington Post, WP Company, https://www.washingtonpost.com/archive/opinions/2002/06/29/pedophilia-and-homosexuality/b385cfb3-8b58-449d-8af9-0cfdcd278978/?noredirect=on.


Sheppard, Simon. (1995 January). The Tyranny of Ambiguity: Homosexuality, The Heretical Press. Retrieved August 19, 2022, from https://www.heretical.com/sgs-2002/toa-s03x.html.


Wilson, Glenn. The Great Sex Divide, pp. 78-80. Peter Owen (London) 1989; Scott-Townsend (Washington D.C.) 1992. https://www.heretical.com/wilson/hbrain.html.


Balthazart, Jacques. (2018 January 9). “Fraternal birth order effect on sexual orientation explained”. Proceedings of the National Academy of Sciences of the United States of America. 115 (2): 234–236. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5777082.


This is not medical advice. You should always consult a medical professional before trying anything that may adversely change your health or lifestyle. This includes anything that involves ingesting ivermectin, turpentine, or other parasite cleansers.

Author: The Pragmatopian & Zero Contradictions

Created: 2023 December 04, 12:21