Sexual attraction is universal in humans. One of the hallmarks of puberty is the arrival of sexual libido, when we see a sharp increase in sexual fantasies and the desire for sex.

There is a prime evolutionary motive to have sex – to reproduce and to pass on our genetic makeup to our offspring. So feeling sexual attraction is a normal, and perhaps defining, feature of being human.

Or is it?

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Several population-level studies have now found that about 1 per cent of individuals report not feeling sexual attraction to another person – ever. When school-aged peers start to talk about finding a classmate "sexy," having crushes or wanting to hook up with someone, these folks simply cannot relate. And they are not bothered or distressed by their lack of sexual attraction.

This is not celibacy, which is the conscious choice to not have sex even though sexual desires may endure. Rather, for these individuals, there is no inherent wish for or desire for sex, and there never has been.

They are asexuals, though many prefer to go by the endearing term "Aces." While asexuals experience no distress over their lack of sexual attractions and desires, the prejudice and discrimination they feel from family, friends and society can be dehumanizing. As a result, many keep their asexuality closeted.

A large online community provides education, support and a space to explore asexuals' experiences (or lack thereof). In 2001, David Jay, then a freshman at Wesleyan University in Connecticut, developed the Asexual Visibility and Education Network (www.asexuality.org), which today is home to a community of 119,000 individuals who identify as asexual.

Part of AVEN's mission is visibility, and the network has made efforts to align with existing LGBTQ groups and societies. They have even made a presence at Pride parades, which celebrate sexual diversity. Some wear T-shirts with the saying "Asexuals party hardest," emphasizing that apart from their lack of sexual attractions, they are no different from the rest of us.

Many asexuals still have romantic attractions – identifying themselves as straight, gay or bisexual romantic – form committed relationships and value all the non-sexual benefits of a partnership that sexual individuals enjoy. Minus the sex.

Critics and skeptics of asexuality question its existence though. They believe asexuals have been abused as children, that they suffer from depression and interpersonal anxiety or that their asexuality may be an extreme type of sexual dysfunction.

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None of the research has supported these claims, however, except for some research suggesting that asexuals are more likely to have Asperger's syndrome (now listed under "autism spectrum disorder" in the Diagnostic and Statistical Manual of Mental Disorders), which is partly characterized by social introversion and a restricted range of interests.

Asexuals have been the subject of many research studies, which has been of benefit both to scientists interested in the complexities of sexual attraction and to asexuals, giving them a greater understanding of who they are.

Most of this research is aimed at understanding asexuality, not framing it as a dysfunction that needs to be cured.

I've been involved in at least a dozen studies examining the experiences of asexuals, testing their sexual response patterns and exploring the biological basis to their (lack of) attractions.

This research has revealed that asexuals are not more likely to have suffered a history of abuse, and do not have higher rates of depression or mental illness than sexual individuals.

When they were brought into a university laboratory, shown erotic films and had their genitals wired to measure sexual arousal, asexual women responded the same as sexual women – with a strong genital blood flow response.

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This tells us that their asexuality is not because of a problem with the plumbing, so to speak. Many asexuals wish to and do procreate – where they differ is in sexual attraction, not in their physical capacity for sex, achieving orgasm or reproducing.

When asexuals masturbate (another issue held up as disproving the existence of asexuality), they report doing so for non-sexual reasons, like an itch that needs to be scratched, or as a means of relaxing and falling asleep. There is also some evidence that asexuality likely developes in utero, just like the bulk of evidence supporting a biological basis for homosexuality.

If you or someone you know can relate to asexuality:

Go online

Visit the AVEN website (www.asexuality.org) and ask questions. Share your experience. You might find that hearing other people's stories confirms your asexual identification, or not, in which case there may be other explanations behind your lack of interest in sex.

Don't assume that therapy or treatment will "restore" your sexual attractions

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Just like conversion therapy does not make a gay person straight, therapy will not make an asexual person suddenly crave sex.

Raise awareness

Many large cities have local meeting groups for asexuals, and some Pride parades have an asexual presence. Get involved in helping stop the stigma.

Participate in studies

Although asexuality has been widely researched for the past 10 years, there is still much we do not know, such as how do asexual men and women differ, what happens to asexuality over a person's lifetime and how to maintain a relationship where one person is sexual and the other is asexual.

Health Advisor contributors share their knowledge in fields ranging from fitness to psychology, pediatrics to aging.

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Lori Brotto is an associate professor of gynecology at the University of British Columbia and a registered psychologist. You can find her at brottolab.com and follow her on Twitter @DrLoriBrotto.