Going Beyond the Lab

Scientists who study the biological roots of sexual orientation should continue working with educators, policy-makers, and the public to put their data to good use.

By Dean Hamer | July 1, 2014

© ALEKSANDAR STOJKOVIC/SHUTTERSTOCKThe biology of human sexual orientation is a fascinating and important area of basic research, but given the intensity of the worldwide social, political, and ethical debates over this topic, it is bound to have consequences outside the lab as well. In considering the social ramifications of this work, it’s instructive to look back at the role that science has played in the quest for lesbian, gay, bisexual, and transgender (LGBT) rights and visibility in the United States over the past 20 years. To ignore the historical record of this shift in public opinion, or even to stifle further research on the basis of unfounded hypotheticals, is a disservice to both science and human rights.

My involvement in sexual orientation research began in July of 1993, when my lab at the National Institutes of Health reported in Science that the maternal but not paternal male relatives of gay men had increased rates of same-sex orientation, suggesting the possibility of sex-linked transmission in a portion of the population (Science, 261:321-27, 1993). This hypothesis was supported by DNA linkage analysis, which demonstrated that gay brothers in these families had an increased probability of sharing certain markers on the Xq28 region of the X chromosome. Our study provided the first molecular evidence for a genetic influence on human sexual orientation—findings that other researchers have recently replicated and confirmed in a large independent study. (See “To Study Unfettered,” here.)

While the claims of our 1993 paper were modest, the reaction was explosive. Headlines referring to our work appeared on the front pages of virtually every major newspaper in the U.S. and across the globe. Time and Newsweek ran pictures of my laboratory. TV and radio stations reported the news, and our work even contributed to the inspiration for a Broadway play (Jonathan Tolins, The Twilight of the Golds, 1993).

Although the research clearly struck a chord, the actual reactions were divided. Some rejoiced because they believed that the findings would bolster the public acceptance and legal status of gay people by showing that sexual orientation was an immutable characteristic, similar to height or eye color. But others lamented the findings, fearing they would be misused to increase discrimination by positioning homosexuality as a genetic disease, allowing prenatal selection against fetuses carrying a gay marker, or surreptitious genetic testing by the military, employers, or insurers.

So what actually happened? Has the genetic research that began two decades ago had a beneficial effect on society, or has it been detrimental?

Clearly, none of the direst predictions have materialized. Same-sex orientation has not been medicalized, nor has there been prenatal or surreptitious genetic testing. On the legal front, the results have been used in several state and federal cases to bolster the argument that sexual orientation is immutable, one of three criteria for heightened constitutional scrutiny of discriminatory laws. It comes as a relief, however, that the Supreme Court, though it has yet to weigh in on the issue, decided to instead strike down the federal portion of the Defense of Marriage Act on the basis of equal protection under the law, thus protecting people’s rights on the basis of fundamental principles of equity and justice rather than any scientific argument.

Ultimately, the most important social impact of research on sexual orientation may be its effect on public opinion. In this regard we are fortunate to have access to extensive data (Public Opinion Quarterly, 72:291-310, 2008; Social Science Journal, 50:603-15, 2013). Since 1977, Gallup has conducted large, representative national surveys that contain various items about sexual orientation, including the question, “In your view, is homosexuality something a person is born with or is homosexuality due to other factors such as upbringing or environment?”

In 1977, only 13 percent of respondents believed people were “born with” homosexuality. But by 2013 that figure had increased to 47 percent. In parallel, the percentage of people who believed that same-sex relations “should be legal” increased from 43 to 64 percent, while those who consider homosexuality “morally wrong” decreased from 53 percent in 2001 to 38 percent in 2013.

While the temporal correlations are suggestive, a more rigorous analysis involves segmenting the population by their belief about attribution (those who believe homosexuality is inborn vs. those who don’t) and comparing the groups’ responses to a series of questions, such as support for same-sex relations, their opinions about same-sex marriage, and their attitudes toward moral acceptability.

Understanding the biological roots of sexual behavior goes beyond pure science, helping to shape attitudes, laws, and, ultimately, the ability of people to live free and open lives.

The results are striking. For every one of these questions, people’s belief about the origins of sexual orientation is the single most important factor in determining their opinions about equal rights. It is more important, by a large margin, than sex, age, education, religiosity, and even self-identification as “born again.” It is also replicable across different survey instruments and samples, and appears to represent a discrete factor independent of liberal or conservative political affiliation (Personality and Social Psychology Bulletin, 32:471-485, 2006).

For example, while most of those who believe that people are born gay agree that same-sex relations should remain legal, nearly 70 percent of people who believe it’s a choice think that antisodomy laws should be reinstated. To put it personally, they think that the discoverer of the Xq28 linkage should be in jail right now rather than engaging in scientific research or writing this essay.

Unfortunately, the positive effects of the scientific findings have been countered by the efforts of anti-gay activists, motivated by religious fundamentalism, to spread their view that people choose their sexual orientation and can change it. Recently, their efforts came to the fore in Uganda, where President Yoweri Museveni initially blocked a vehement anti-gay law as discriminatory because he considered homosexuality to be an inborn trait comparable to albinism. But when his Ministry of Health—using words and arguments drawn directly from anti-gay and anti-science religious groups from the United States—issued a report concluding that there is “scientific proof that homosexuality is not genetic,” Museveni changed his mind. Although the Ugandan president has issued a call to the United States government for scientific advice and assistance, there has been no official response.

The events in Uganda illustrate that the real danger is to ignore the science of human sexuality. In this, as in so many areas, what drives prejudice and discrimination is ignorance, not knowledge. Understanding the biological roots of sexual behavior goes beyond pure science, helping to shape attitudes, laws, and, ultimately, the ability of people to live free and open lives. It thus behooves scientists who conduct such research to be thoughtful participants in how their data are presented and play out in the public forum. This is why I continue to believe, as I stated in Science more than 20 years ago, that “scientists, educators, policy-makers, and the public should work together to ensure that such research is used to benefit all members of society.” 

Dean Hamer is a geneticist and scientist emeritus at the National Institutes of Health, where he conducted research and directed the National Cancer Institute’s Gene Structure and Regulation Section for 32 years. He coauthored the 1994 book The Science of Desire: The Search for the Gay Gene and the Biology of Behavior with Peter Copeland.

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Avatar of: James V. Kohl

James V. Kohl

Posts: 525

July 1, 2014

The Mind's Eyes: Human pheromones, neuroscience, and male sexual preferences, was concurrently published as a book chapter in the Handbook of the Evolution of Human Sexuality. The model represented what was known in 2006 about cell type differentiation, which occurs via nutrient-dependent pheromone-controlled alternative splicings of pre-mRNA in species from microbes to man.

Gay, Straight, and the Reason Why: The Science of Sexual Orientation

"This model is attractive in that it solves the "binding problem" of sexual attraction. By that I mean the problem of why all the different features of men or women (visual appearance and feel of face, body, and genitals; voice quality, smell; personality and behavior, etc.) attract people as a more or less coherent package representing one sex, rather than as an arbitrary collage of male and female characteristics. If all these characteristics come to be attractive because they were experienced in association with a male- or female-specific pheromone, then they will naturally go together even in the absence of complex genetically coded instructions."

The key issue has always been the absence of complex genetically coded instructions because it is the epigenetic landscape that links sexual orientations to the physical landscape of DNA in the organized genomes of species from microbes to man via conserved molecular mechanisms.

Avatar of: W. Boernke

W. Boernke

Posts: 18

July 8, 2014

"For example, while most of those who believe that people are born gay agree that same-sex relations should remain legal, nearly 70 percent of people who believe it’s a choice think that antisodomy laws should be reinstated. "

"A plague on both your houses."

All biological traits are subject to natural selection. Natural election is defined as differential rates of reproduction. What is a homosexual's rate of reproduction?

If people are born gay, then homosexuality can't be immoral. Nonsense. We are all born with the ability to become angry, yet we condemn the behavior road rage. I'm surprised gay rights activists would adopt biological determinism as an argument, for this puts them in the camp of racists who think blacks are genetically inferior to whites. The Nazis thought Jews were a subhuman race, despite the fact Einstein was a Jew.

The argument of homophobes that homosexuality is a sin because X says so (here pick your ancient code: the Torah, Islamic Sharia, the Code of Justinian--a Christian Roman Emperor) is also nonsense.

The Supreme Court struck down anti-sodomy laws (Lawrence v. Texas) for the same reason the First Amendment prevents the establishment of a theocracy. In Reynolds v. the US, the court held that only freedom of belief is absolute (you have the right to believe anything, no matter how nonsensical). Freedom of religious action is not absolute, if it were, then one could practice human sacrifice because the gods demand blood. (It is too bad that the court forgot this decision when they ruled on the Hobby Lobby case. Hobby Lobby has the right to believe birth control is a sin, but they do not have the right to break the law because of their religious duty to avoid sin.)

The notion that there is a biological basis for sexual orientation is simply nonsense. Consider the ancient Greeks. Unlike the ancient Israelites, the Greeks did not condemn sodomy. In fact Greek soldiers were encouraged to take male lovers because a man is highly motivated to fight when fighting alongside a male lover. Alexander the Great had male lovers. When he realized he needed a male heir, he married Roxanne. If you could ask Alexander if he was born gay or straight, he would probably have thought you are crazy. When I am conquering the world, I will have male lovers, but because reproduction is essential for the survival of the species, I will marry and produce little Greeks.

Sexual orientation, like religious orientation, is the result of cultural evolution, not biological evolution.

Avatar of: Kathy Barker

Kathy Barker

Posts: 44

July 8, 2014

I like the fact that this article was written, and the suggestion that scientists should work with poliymakers and the public to benefit all members of society.

But I don't think biological determinism is any better a basis for a moral code or a cultural norm than religion.

A world in which homosexuality is just fine is good for individuals and for our societies for many political, philosophical, and personal reasons. But aren't we painting ourselves in a corner by linking genetics with acceptance? Simplistically, wouldn't this suggest that rape, is okay because boys will be boys? 


Avatar of: Kathy Barker

Kathy Barker

Posts: 44

July 8, 2014

But this is a terrific article. Yes, science can explain why things are they way they are, but we work with others to decide how things should be.


Avatar of: Salticidologist


Posts: 56

July 8, 2014

A scientist should, in the capacity of scientist, stay out the any 'moral' implications of any kind of behavioral research.  There are none.  For example, one could view the discovery of a genetic anomaly as either 1) The mark of Cain, 2) A defect to be treated with medication or gene therapy, 3) A cause to remove a person from the rest of society, or 4) A source of pride in the diversity of life.  Science does not pick an option, human societies do.  To remain objective, science must remain neutral.  Otherwise, it is not to be trusted.

Avatar of: Salticidologist


Posts: 56

Replied to a comment from Kathy Barker made on July 8, 2014

July 8, 2014

Yes, the argument of morality from biology is nonsense.  For example, male lions benefit by killing the offspring of their rivals.  Should we follow their example?  Science does not judge the morality of Panthera leo, and it cannot judge the morality of Homo sapiens either.

Avatar of: Roy Niles

Roy Niles

Posts: 115

July 10, 2014

I see that James V Kohl, commenting above, is babbling that somehow pherenomes and genetic traits are causatively connected.  He has a factory that makes perfume and apparenlty has a bottle that makes men think other men are another form of women.  Which of course they are, since only women grow them.  Now if he could make a perfume that would either grow a set testicles or ungrow them, he'd make millions.  

July 10, 2014

The language used in the statement "For every one of these questions, people’s belief about the origins of sexual orientation is the single most important factor in determining their opinions about equal rights." is misleading. The data presented are correlations. Whether opinions about equal rights "determine" belief about origings of sexual orientation, or vice versa as stated by the author, or other unmeasured factors determine both attitutes is not shown in this research. Correlations do not imply causation. One cannot determine whether belief about biological origins of homosexuality are causally related to the other beliefs. I support gay rights, as well as other individual rights, and I am interested in biology. However, I don't think that biology has an real role in determining public opinion about gay rights. Opinion will guide how the science is used, not the other way around. Anti-gay Eugenicists could take the same data to prevent reproduction in those families, for example. At this time in our society, Eugenicists are (rightly) out of favour, and there is increasing support for gay rights, so it is not a surprise that more people use the sciences to defend gay rights than vice versa, such that those beliefs correlate.

Avatar of: darwinbot


Posts: 12

July 20, 2014

I agree with other commenters that 'morality' should not be based on biology--and in the particular case of gay rights, if we keep countering the anti-gay movement's arguments with a lack of choice in matters of sexual orientation: what happens should we ever discover that sexual orientation has little or no genetic basis?

Gays should be allowed to marry, for example, because it's not anyone's business whom I decide to share my life with, whether a choice or genetically determined, as my rights in this sphere of life do not encroach on anyone else's--and that should be the only measure of moratlity: who, if anybody, is affected by my behaviour, and in what ways? Being 'personally offended' by the existence of homosexuals based on a 3000-year-old book of nonsense is not a valid example of anyone's rights being violated...

Avatar of: Dean Hamer

Dean Hamer

Posts: 2

July 22, 2014

I appreciate The Scientist publishing this article.  It was a great opportunity to explore some of the social issues associated with scientific studies of sexual orientation.  However, I am surpised and disapointed that so many of the commentors have either not read or not understood the article, instead jumping to the incorrect assimption that I think that biology should determine morality - the *exact* opposite of the actual conclusion.  


Comments shoudl reflect the actual content of the article.  This isn?t the place for rants.

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