Two years ago, Dan Ritter, 19, found himself spending most of the summer fighting off a girl's sexual advances. There wasn't anything wrong with the girl, he wants to clarify. He just wasn't sexually attracted to her. In fact, Ritter started to realise he wasn't attracted to anyone. "Slowly, I noticed that I was completely uninterested in sex," he says. Then, in May 2012, Ritter came to an epiphany: "I'm asexual."

It's estimated that 1 per cent of all people have no sexual desire towards others whatsoever. One British study that queried 18,000 people about their sexual practices included the option, "I have never felt sexually attracted to anyone at all." One in a hundred people ticked the box.

Low libido: Jo Qualmann describes herself as being in a “committed platonic relationship”.

However, that doesn't always mean a lack of sexual drive. In one study, US sexologist Lori Brotto estimated that half of all asexuals masturbate on a fairly regular basis; some have an aversion to all human contact, others need it as much as anyone else. Determining the root causes of asexuality is tricky, as few studies on the subject have been done. And asking asexual people why they think they're asexual - is it the result of sexual abuse? Sexual confusion? A biological flaw? Not finding the right person yet? - becomes an exercise in asking the same horrible questions gays and lesbians have copped for years. Some feel they were born asexual; others identify as "acquired" asexuals. "And if we're happy," one asexual person told me, "why does it matter?"

In 2004, New Scientist said, "If asexuality is indeed a form of sexual orientation, perhaps it will not be long before the issue of 'A' pride starts attracting more attention." By then, though, the asexuality movement was already well underway. In 2001, David Jay - a handsome, articulate American Gen-Y spokesperson - founded the Asexual Visibility and Education Network (AVEN), selling shirts with slogans like, "Asexuality: it's not just for amoebas any more." And in the last few years, celebrities such as Janeane Garofalo, Morrissey and Deerhunter frontman Bradford Cox have all publicly declared themselves as asexual. Asexuality has even been around long enough to have its own stereotypes (asexuals apparently all like Doctor Who and cake).