The arrival of LGBT Pride Month provides a momentous opportunity for us to celebrate this community and reflect on the strides it has made over the course of U.S. history. But instead of marching in remembrance of the Stonewall riots in 1969, this year’s Pride Parade in Los Angeles has been renamed the Resist March and will protest recent decisions made by the Trump administration, offering a reminder that the battle for sexual minorities’ rights has yet to be won.

Research on the topic of sexual orientation usually conjures both widespread fascination and controversy because it is frequently used to inform both public policy and cultural understanding. As a neuroscientist, I have watched as neuroimaging technology has improved in recent years, allowing researchers to make huge advances in revealing the neural underpinnings of human sexuality. But as we marvel at how far we’ve come, it’s crucial to recognize that the social—and moral—acceptance of a person’s sexuality shouldn’t depend upon their interests being biological in nature.

Sexual orientation is defined as the sexual attraction to women, men or both sexes; it is whom we find ourselves attracted to from an early age. Within the field of sexology, sexual orientation is generally understood to be innate.

The most up-to-date research has demonstrated differences in the brain associated with being gay, which has offered evidence that sexual orientation is not a choice. In 1991, British-American neuroscientist Simon LeVay published a seminal study looking at the third interstitial nucleus of the anterior hypothalamus, which is involved in regulating sexual behavior and is known to be larger in men than women. LeVay found that this part of the brain was not only smaller in homosexual men versus heterosexual men, but also more similar in size to that of heterosexual women. This suggested that the brains of gay men were partially feminized.

Social—and moral—acceptance of a person’s sexuality shouldn’t depend upon it being biological in nature.

Since then, a wealth of research has shown that being gay is associated with differences in how a person’s brain developed in the womb and in the critical period just after birth. In the same vein, research on the topic of digit span ratio—which compares the length of a person’s index and ring fingers—has put forth evidence that the brains of lesbian women were partially masculinized. Across a variety of animal models (including rats, ferrets and sheep, since it’s not ethical for us to use unborn human babies as test subjects), changing the amount of testosterone an animal is exposed to changes whether they are sexually interested in same-sex or opposite-sex mates.

These studies lent credibility to the idea that being gay is biological and called into question early theories that claim sexual orientation is a lifestyle choice or the result of upbringing. Since then, brain imaging has been widely used to understand the sexual preferences of other sexual minority groups.

For example, a study published earlier this year in Nature’s Scientific Reports showed, for the first time, brain differences associated with being bisexual. Using functional MRI, sex researchers at Northwestern University compared the activation patterns of gay, straight and bisexual men. Unlike gay and straight men, who displayed patterns denoting sexual arousal when looking at images and videos of men or women, respectively, bisexual men showed similar patterns when looking at both sexes. These findings called into question the popular belief that bisexual men are actually closeted gay men.

Perhaps most surprisingly, emerging research has pointed to an underlying biological basis to asexuality. In a 2014 study of 325 asexual people, being asexual was correlated with higher rates of non-righthandedness, which is a known biomarker for brain differences related to sexual orientation. The researchers concluded that a lack of sexual attraction toward other people may paradoxically be its own form of an orientation, which confirms—contrary to what many people still believe—that asexuality does indeed exist.

When we take a step back and look at these research findings on the whole, it makes sense why other sexual minority communities would feel the pressure to describe their sexual interests as either biological or like a sexual orientation. It’s not uncommon to hear people talk about “feeling different” from a young age or—hat tip to Gaga—being “born this way,” even when their sexual preferences are very much a conscious choice.

Biological explanations for sexual orientation have gained mainstream acceptance in recent years and have helped affect attitudes and understanding around differences in sexual identity; not just in terms of tolerance and acceptance, but agreement that a person shouldn’t have to change what they’re into.

We should want to understand variations in human sexuality because this gives us insight into what it means to be human.

I’ve seen in my own research how people with atypical sexual interests experience heavy stigma and pressure to conform to societal norms. It’s not unusual for someone to lose family and friends and experience mental health issues as a result of not the interests themselves, but the ostracization they receive from our society.

In fact, there is a documented link between tolerance around being gay and a person’s beliefs about the origins of sexual orientation: people who believe that sexual orientation is inborn are more likely to be in favor of equal rights for non-heterosexual people, a finding that has been stable since the 1970s.

Much of such support has crystalized from watching the ways in which some approaches, like the now-discredited conversion therapy, exploited the belief that being gay was learned in order to justify unethical attempts at turning gay people straight. The truth is, whether or not a person’s sexual preferences are beyond their control has no relevance regarding whether or not they should be accepted. When sexual preferences are due to personal choice, they too should be viewed as legitimate.

Nowadays, the field of sex research has become a political minefield, so it’s worth mentioning that when certain research findings are considered politically taboo, it undermines researchers’ abilities to do this kind of work, which leaves important scientific questions hanging in the dark. We should want to understand variations in human sexuality because this gives us insight into what it means to be human—not because the answers will help lend legitimacy—or favorable policy—to one particular group.

Discrimination stems from a lack of understanding, and although biological studies may help bring about superficial social acceptance, they don’t address the fears and intolerance lurking beneath. So long as a person’s sexual interests are safe and consensual, they shouldn’t need to rely on biological justifications to be free from judgment and persecution, or to be afforded the same basic human rights and legal protections as everyone else.


Debra W. Soh is a sex writer and sexual neuroscientist at York University in Toronto. She has written for Harper’s, Scientific American, The Wall Street Journal, The Los Angeles Times, The Globe and Mail and many others. Follow her on Twitter: @debra_soh.