Ah, to be 21 years old again. A typical night out for me consisted of throwing on the skimpiest outfit I could find, paired with impossibly high heels, and meeting up with my gay boys at someone’s apartment to drink and kiki. This would last a few hours before the neighbors would complain about the noise and we’d stumble over to the local drag show or club. There would always be lots of drama, whether it was bumping into your friend’s ex who was guilty of cheating or some random boy elbowing you on the way to the coat check. The night would usually culminate in someone crying or throwing up in the bathroom, and we would all take that as a pretty good sign that it was time to go home.

Something about spending my formative adult years immersed in the gay community bestowed upon me, even a decade later, the impeccable ability to tell—within two seconds of meeting someone—whether he is gay. Now, a recent review paper in the Archives of Sexual Behavior confirms, for the first time, that gaydar isn’t a myth: It turns out we’re able to tell someone’s sexual orientation “accurately” from surprisingly subtle cues in their speech, mannerisms and physical appearance.

Although it’s stereotyping, the tendency for gay men to appear more feminine than straight men, and for lesbian women to appear more masculine than straight women, has a long history, dating back to the 1860s. Back then, a German lawyer named Karl Heinrich Ulrichs proposed a theory about homosexuality in which gay men were female souls trapped in men’s bodies and lesbian women were male souls trapped in women’s bodies.

We can acknowledge that there are identifiable differences between gay and straight people without being homophobic.

Although we’ve come a long way since the 19th century, recent research has offered support for the core idea behind Ulrichs’ theory, including neuroimaging studies showing that the brains of gay men and women are, respectively, partially feminized and masculinized. Reserach has also shown genetic underpinnings to homosexuality. Based on these findings, one would expect corresponding differences in behavior associated with sexual orientation.

Indeed, studies have shown differences in speech patterns associated with sexual orientation, which is probably one of the first things that come to mind when we think of differences between gay and straight folk. For example, gay men are more likely than straight men to have a lisp, and this is usually perceived by other people as a cue that he might be gay. In one study from almost 20 years ago, participants listened to tape recordings of straight and openly gay men speaking. Study participants were able to correctly identify the speaker’s sexual orientation roughly 80 percent of the time, despite the fact that participants also showed a bias toward identifying speakers as straight.

There are also documented differences between homosexual and heterosexual people with regard to their physical mannerisms. For instance, research has shown that people are able to tell someone’s sexual orientation from the way they walk. Gay men sway their hips more, while lesbians are more likely to swagger their shoulders.

Regarding physical appearance, we can glean a huge amount of non-verbal information by looking at a person’s face, and a complex system of mechanisms in the brain have evolved to help us with this process. This also extends to sexual orientation; despite having low confidence in their judgments, people are able to accurately identify someone’s sexual orientation within one-twentieth of a second of looking at their face.

Researchers at Brock University in Canada also found that our facial features differ according to our sexual orientation. Overall, gay men tend to be baby-faced, with more feminine facial features, while lesbians tend to have a more masculine facial structure. Compared with straight men, gay men tend to have noses that are shorter and rounder. Compared with straight women, lesbians tend to have mouths and noses that are tilted upwards, resembling the facial features of straight men.

Clothing is another way in which people tend to pick up on sexual orientation. Gay men have been shown to invest more money and time on their appearance than straight men, and to use clothing as a way of differentiating themselves from not only straight men, but other communities within gay culture—which becomes clear when you think of how different, say, leather daddies look compared with your average twink or otter.

This tendency to use clothing to signal a person’s sexual orientation can also be seen in lesbians. Many lesbian women, after coming out, will change the way they look, including cutting their hair short and going make-up-free.

What does this all mean, in the bigger picture? Life is hectic and complicated, and we, as human beings, have evolved the ability to read social information quickly and reliably. Since many aspects of who we are, like sex, age and race, are quite obvious from the get-go when we take a gander at someone, it follows that sexual orientation would be, to some extent, similar. Being able to correctly identify whether someone is gay or straight helps us in our pursuit of finding a suitable mate, and research has actually shown that straight women’s gaydar improves when they are in the fertile period of their menstrual cycle.

I’ve also been hearing a lot lately about how sexual orientation and gendered behavior are two completely unrelated things, but the reality is—at least from a scientific perspective—they are interconnected and, as you’ve seen, noticeable across a wide range of measures across many different sub-disciplines within sexology. We can acknowledge that there are identifiable differences between gay and straight people without being homophobic.

Perhaps the most important thing I took away from the paper was that people with higher anti-gay prejudice have less accurate gaydar because they tend to assume that everyone is straight. I’d argue that pretending gay people are the same as straight people, besides whom they go to bed with, only does a disservice in battling this ignorance and obtaining equal rights and representation for the community. That being said, even if you think you have perfect gaydar, you should never assume any person you meet is gay or lesbian based on signs alone, nor corner them with the question. One of the most important rights a gay person has is the right to come out on their own terms.

Debra W. Soh is a Toronto-based sex writer with a PhD in sexual neuroscience from York University. She has written for Harper’s, Scientific American, The Wall Street Journal, The Los Angeles Times, The Globe and Mail and many others. She tweets @DrDebraSoh.