September 28, 2019 | Jerry Bergman

Massive Study Finds No Evidence of a Gay Gene

by Jerry Bergman, PhD


Homosexual behavior has always been a challenge to explain by evolution. As one anthropologist, R. C. Kirkpatrick, writes

Homosexuality presents a paradox for evolutionists who explore the adaptedness of human behavior. If adaptedness is measured by reproductive success and if homosexual behavior is nonreproductive, how has it come about?[1]

The replacement rate is 2.1 children per married couple, and in many countries the replacement level is significantly below this, causing not population growth, but decline. This is a growing concern that homosexuality exacerbates. The rate of children for gay couples is consistently far below that of heterosexual couples.[2] And the growth of homosexuality acceptance has resulted in far fewer children per couple because two males and two females are not able to have children as a couple.[3] Methods by which they produce a family include adoption, foster parenting, donor insemination, surrogacy, and children from previous heterosexual relationships. By  adoption alone, LGBT couples are four times more likely than heterosexual couples to have an adopted child in their household. In 2013, 13 percent of LGBT families had an adopted child, in comparison to only three percent of opposite-sex couples.[4]

The Gay Gene Theory

X and Y chromosomes differ dramatically in size and content

In 1993 a study by Professor Dean Hunter linked the region of the human X chromosome, xq28, to male homosexuality, and the “gay gene” idea was born.[5] Although the idea that homosexuality had a biological origin was widely accepted before this, the 1993 study was reflected in claims like, “I was born this way.” The Democrat Presidential candidate Pete Buttigieg has asserted, “God made me gay and who can disagree with God?”[6] He defends his sexual orientation with remarks like, “if you have a problem with who I am, your …  quarrel, sir, is with my Creator.”[7] The fact is, no one has been able to successfully replicate Hunter’s research findings. This was further complicated by the allegation that a junior researcher in Hunter’s laboratory alleged that Hunter, (who identifies as gay), selectively presented the data by dropping cases that did not fit his theory as published in his 1993 paper in the journal Science.[8] As could be expected, Hunter denied the allegations.

Finally A Large Study Helps Answer this Question

The latest study—the largest ever completed—was conducted by an international group of scientists and published in the most prestigious science journal in America, Science.[9] The study used a genome-wide association study that included genomes of 408,995 individuals in the health resource British Biobank. It also included 68,527 American users of the popular genome-sequencing company 23andMe. The combined number of participants in the study dwarfs all previous research. In short, according to Dr. Saey, Ph.D. in molecular genetics from Washington University in St. Louis, the conclusion is clear.

“There is no ‘gay gene’ that determines whether someone has same-sex partners,” says Andrea Ganna, a geneticist at …  MIT and Harvard … . Family studies have suggested that genetics account for about 32 percent of heritability of homosexual behavior. But each …  [gene] has a very small effect on whether someone has ever had a same-sex sexual partner, the new research found.[10]

This small effect could include certain behaviors that have little directly to do with homosexuality, such as high levels of masculine traits in females (most who marry and adjust well in society) and high levels of feminine traits in males (most who also marry and adjust well in society). Given the normal curve, we expect to find a few people at the two extremes of the femininity/masculinity distribution curve. In other words, a few males will be firmly in the female part of the curve and a few females will be firmly in the male part of the normal curve.

Characteristics of femininity are not universal. Nevertheless, general patterns do exist. Gentleness, empathy, sensitivity, caring, sweetness, compassion, tolerance, nurturance, deference, and succorance are traits traditionally cited as feminine. The same is true of masculinity, which includes traits like strength, courage, independence, leadership, and assertiveness.

The journal Nature was definitive in its headline:

“No ‘gay gene’: Massive study hones in on genetic basis of human sexuality. Nearly half a million genomes reveal five DNA markers associated with sexual behaviour — but none with the power to predict the sexuality of an individual.[11]

The researchers used a method known as a genome-wide association study (GWAS) to evaluate the genomes of hundreds of thousands of people for single-letter DNA differences, called single nucleotide polymorphisms (SNPs, often pronounced ‘snips’). If people with a certain trait in common, such as homosexual behavior, also share certain SNPs, chances are that the SNPs are in some way related to that characteristic.

Sampling Issues

The researchers divided the main study participants into those who reported having had sex with someone of the same sex, and those who did not.[12] The problem with this division—among others—is that many people who have had reported sexual encounters with a person of the same sex include youths experimenting, especially youths attending all-boys schools, inmates in prisons, inhabitants in monasteries, and others deprived of normal heterosexual social communities. Some of those reporting having had homosexual encounters early in life likely went on to normal heterosexual relationships. This fact could further skew the interpretations of small genetic associations that were reported in the study, misleading readers toward notions that homosexual behavior has at least some potential genetic basis.

Auxiliary Data

The researchers also included a smaller database, the Molecular Genetic Study of Sexual Orientation (n = 2,308 U.S. adult males), in which respondents were asked about their sexual identity. Another study was included (n = 4,755 U.S. young adults), in which respondents were asked whether they ever had same-sex intercourse and were romantically attracted to the same sex. The Child and Adolescent Twin Study in Sweden (n = 8093 Swedish adolescents) was also included, in which participants reported the degree of attraction to the same versus opposite sex. These additional studies supported the basic findings.[13]

Combined Genetic Influences Minor at Best

Altogether, the tested genetic variants accounted for a mere 8 to at most 25 percent of the variation. If the population was not limited to exclusively homosexual, 7 on Kinsey scale (1 was exclusively heterosexual to 7, exclusively homosexual), the numbers would likely be less than these variances indicate, if some of the qualifiers used in the small studies had been consistently used in both of the larger studies. A total of 26,827 individuals reported same-sex sexual behavior – a high number, quite probably because those who self-selected to report homosexual behavior were more likely to be homosexual. Another reason for the high number could be cultural. Evolutionist Michael LePage surmised in New Scientist, “Until it became acceptable for same-sex couples to live together in western countries, many homosexual people had partners of the opposite sex. In some traditional societies, various forms of non-exclusive homosexuality were common.”[14] Understandably, homosexuals in earlier times would try to conceal their behavior with various ruses, like pretending to have a heterosexual consort or spouse, and many formally married. When I worked at Arlington Psychological Associates as a therapist, several of my patients were happily married. The “gays” were there for therapy for other issues including, in one case I knew, the death of her spouse. He was a known gay man, she heterosexual and never could deal with his loss.

Significantly, “In all cases, the variance explained by the polygenic scores was extremely low (<1%); [consequently] these scores could not be used to accurately predict sexual behavior in an individual.”[15] Since prediction is considered valuable for confirming scientific theories, the small remaining fraction of variants that may be associated with homosexuality really have no scientific value. An individual may possess all the variants and yet have no homosexual tendencies. The statistics indicate, in fact, that the vast majority (75 to 92 percent) with these genetic variants will not be influenced in the direction of homosexual behavior by them.

A part of the study rarely reported by the press include the associations of these genetic indicators with mental health problems, which

are substantially heritable, and previous population surveys have shown elevated risk of adverse mental health outcomes (such as depression, anxiety, or substance use) in sexual minority populations, including individuals engaging in same-sex sexual behavior. We found several personality traits (loneliness and openness to experience), risky behaviors (smoking and cannabis use) and mental health disorders…. in both sexes that same-sex sexual behavior was positively genetically correlated with several psychiatric or mental health traits.

They also found “Some associations were sex specific. In particular, the genetic correlations with bipolar disorder, cannabis use, and number of sexual partners were significantly higher in females than in males.”[16] Lastly, it was found that the increased rate of reported same-sex sexual behavior across time, raises

questions about how genetic and socio-cultural influences on sexual behavior might interact. We also observed partly different genetic influences on same-sex sexual behavior in females and males; this could reflect sex differences in hormonal influences on sexual behavior (for example, importance of testosterone versus estrogen) but could also relate to different sociocultural contexts of female and male same-sex behavior and different demographics of gay, lesbian, and bisexual groups.[17]

Objections to the Study

The researchers anticipated objections to the study, and so communicated the results with different LGBTQIA+ groups (meaning lesbian, gay, bisexual, transgender, queer, intersex, asexual, and other+ groups) to try to appease them. In spite of their efforts, however, objections persisted.[18] Some members of the LGBTQIA+ community argued that the study should not have been carried out at all.. Some may have worried that the lack of a genetic cause could lead to more discrimination, because it would make homosexuality a choice, not an inborn trait. The openly-gay evolutionary biologist and anti-creationist Douglas Futuyma wrote in a 2005 essay, “There is only a short distance between understanding the genetic or environmental origins of sexual variation and the possibility of intervention – [in] medical terms, ‘cure.’” [19]


The study supports the importance of the environment, especially early experiences with homosexual behavior. Genetic influences, at best, were only minor and equivocal. It also makes the oft-repeated claim, “I was born this way,” less plausible, which may explain the LGBTQIA+ objections to the study. Ironically, attempts to explain homosexuality by evolution, all of which have failed, is not a concern if the behavior is environmental rather than genetic.[20] In view of the findings of this study, it is obvious that evolutionary attempts to explain homosexuality are contrived theories, not based on fact.


[1] R. C. Kirkpatrick, 2000. “The Evolution of Human Homosexual Behavior,” Current Anthropology, 41(3): 385-413, June 2000.
[2]Andrea Ganna, et al., 2019. Large-scale GWAS reveals insights into the genetic architecture of same-sex sexual behavior. Science, 365(7693):1-8, p. 882.
[3] Peter Sprigg, 2012. HOMOSEXUAL PARENT STUDY, Summary of Findings
[4] Gary J. Gates and M.V. Lee Badgett, 2007 Adoption and Foster Care by Gay and Lesbian Parents in the United States, 2007 ;
[5] R. Pool,  (July 1993). “Evidence for homosexuality gene.” Science261 (5119): 291–292; King, M.C., (July 1993). “Human genetics. Sexual orientation and the X.” Nature364(6435): 288–289.
[6] Nick Nelson, 2018. Father Nick Nelson: Does God ‘make’ people gay?
[7] ‘Mayor Pete’ To Pence: God Made Me Gay
[8] J. Kaiser, (28 Feb 1997). “No Misconduct in ‘Gay Gene’ Study.” Science275(5304): 1251. doi:10.1126/science.275.5304.1251b. ISSN 1095-9203. PMID 11644902.
[9] A scientific study has established that there is no “gay gene.”
[10] Tina Hesman Saey, 2019, There’s no evidence that a single ‘gay gene’ exists.
[11] Jonathan Lambert, 2019.
[12] Ganna, et al.; Ref. 2, p. 881.
[13] Ganna, et al.; Ref. 2, pp. 881-882.
[14] August 29.
[15] Ganna, et al.; Ref. 2, p. 884.
[16] Ganna, et al.; Ref. 2, pp 884-885.
[17] Ganna, et al.; Ref. 2, pp. 886-887.
[18] Ganna, et al.; Ref. 2, p. 889.
[19] Angus, Chen, 2019. Study Finds No ‘Gay Gene,’ But Some Question Whether The Search Should Have Started At All.
[20] Kirkpatrick, Ref. 1. Although Kirkpatrick proposed his own theory, it too is problematic.

Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology at several colleges and universities including for over 40 years at Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored, are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.

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