"OK," writes Annette, in an introductory email: "I am 47 but look younger, probably because I take good care of myself and also do not have the stress of a husband and kids." At first glance it reads like the "describe yourself" section of a dating site, which is ironic, considering that Annette is one of several people responding to my search for case studies on a forum for people who are asexual. That is, people who have little to no interest in sex. "I live in a dull suburb in Minnesota and right now I'm eating lunch (and typing) at the law firm where I work as a paralegal. My job makes me happy to be asexual, as I see all the divorce cases and what really goes on. Yeah, really – the crap that is going on in the suburbs: her husband left her for his boyfriend, stuff like that."

Annette writes in the breathless, self-assured style of any typical, busy American too pushed for time to mince their words. Life as an asexual person in the suburbs has thrown her some curveballs, like the woman at her local church group who prayed she would find a husband, chanting: "Saint Anne! Saint Anne! Find her a man!" Or the time a relative, apparently perplexed by Annette's perpetual singledom, secretly signed her up to a dating agency. She's still getting newsletters from the company years later.

It's estimated that 1% of the world's population is asexual, although research is limited. Annette and others like her have never and probably will never experience sexual attraction. She has been single her whole life, something she repeatedly says that she is more than happy about. In a developed-world country, especially one where Christianity casts a long shadow over politics and the government, it's hard to see why not wanting to have sex would be a problem. But Annette has spent her life feeling misunderstood while simultaneously failing to comprehend what motivates those around her. When she wants to talk about politics, her colleagues want to talk about their "crappy husbands".

General public ignorance about asexuality can cause a surprising array of problems, even in these sexually enlightened times. This is why David Jay, the charismatic San Franciscan who has become a poster boy for asexuality, set up the Aven website (Asexuality Visibility and Education Network) in 2001, an online community that has grown to include more than 50,000 members who lie somewhere on the spectrum of asexuality. Jay is the focus of a new documentary called (A)sexual, in which he explains the "icky mystery" of going through adolescence without developing sexual attraction.

In the opening scenes of the documentary, director Angela Tucker asks people to tell her what asexuality means to them. "I think… moss is asexual?" one woman ponders, while another talks about tadpoles.

Listen to asexual people talk about everyday life and you realise they face social minefields that don't affect people of other sexualities. "Living in a world that holds the romantic and the sexual as the highest ideals possible is difficult," says Bryony, a 20-year-old biology student from Manchester. "The most pervasive effect on my life at the moment, as a student, is how many conversations revolve around sex and the sexual attractiveness of certain people that I just don't really want to join in with."

Jay tells me over the phone from his home in San Francisco that he thinks what the community often refers to as the "asexuality movement" is now in its third phase. Roughly speaking, the first phase began in the early 2000s, which isn't to suggest that asexuality didn't exist before – simply that it didn't have a coherent public identity. It was about identifying exactly what asexuality was: not the suppression of sexual desire, which is celibacy, but the absence of it. The internet facilitated asexuality's going overground; whereas it used to be associated with amoebas and plants, the turn of this century saw Yahoo forums opening up around the first people who, anonymously and tentatively, said: "I just don't get what all the fuss about sex is."

Phase two involved mobilisation. In 2006 David Jay hit the media with his message about asexuality. People were curious, but the response was brash and superficial. Appearing on The View, a US panel show not unlike ITV's Loose Women, Jay attempted to explain to mainstream America what asexuality was. "What's the problem? Why do you need to organise?" barked Joy Behar, an actress and comedian who looks like Bette Midler and makes Joan Rivers seem demure. "If you're not having sex, what's there to talk about?" said her co-panellist Star Jones, in an "Am I right, ladies?" tone of voice. The panel was playing for laughs, but the women immediately offered alternatives to Jay's assertion that he doesn't experience sexual desire. "Maybe it's repressed sexuality. Maybe you don't want to face what your sexuality means," said Behar, before the women joked about making Jay "lie down". "To be analysed or for something else?" they cackled.

In 2012, phase three of the asexuality movement, as Jay defines it, is about challenging the mainstream notion of what constitutes a normal sex drive. And that's when things get tricky. "Theoretically the absence of sexual desire shouldn't be a problem," says Dr Tony Bogaert, an associate professor at Brock University in Ontario who specialises in research into asexuality. "But ours is a media which suggests hypersexuality is the norm. Potentially, asexuality has become a 'problem' as it became more visible, and in a sense it's become the new stigma."

Suzie King, a counsellor and the founder of the UK dating website Platonic Partners, says that her patients often report a lack of awareness or understanding in the therapeutic industries when presented with asexuality. "That the industry wants to 'fix' asexuals and make them sexual is the most common comment I have heard; there is not much attention paid to the real psychological and emotional needs of asexuals."

Loneliness seems to be a recurrent issue for asexual people, and was even more so before the internet became a common way to reach out to other people under the cloak of anonymity. Sex, of course, forms only one part of a meaningful relationship, but if it is thought to be an indispensable part, then those who do not wish to have sex may also conclude that they are unable to have a relationship. Suzie King set up Platonic Partners in 2007 after a patient of hers attempted suicide. "He was deeply lonely and could not foresee a future in which someone would be willing to have a relationship with him without sex." Fortunately King was able to introduce him to a woman for whom no sex life was not a problem.

"How many times have you heard someone say: 'I hate my job, but coming home to my husband/wife makes it worth it'?" asks Bryony. "For a while I was very worried about how I'll never have that. My ideal would be to live in a commune-type set-up with some close friends, but as they grow up and form monogamous relationships I'm worried that that's going to become less likely. I'm a little jealous about people who have that one person that they would do anything for and who would do anything for them in return, but my aim is to get the same emotional connection on a platonic level with friends."

Platonic Partners caters not only for asexual people but also for the sexually impotent and for those who cannot have sex because of injury. But whatever the reason, the central message is the same: just because you don't want to or can't have sex, it doesn't mean you should spend your life alone. In the documentary (A)sexual, David Jay says: "When I came out to my parents they immediately told me not to limit myself. I think they had a hard time seeing how I could be happy without sexuality being part of my life."

Other experiences suggest that parents would have an easier time accepting their child coming out as gay, and that their responses are similar to those who did just that in previous eras: "Are you sure? Maybe you'll grow out of it? What about grandkids?"

Teenagers at the Gatecrasher Ball in London. Photograph: Rex Features

Part of what is so fascinating about the asexuality movement is the broad spectrum of sexuality that it reveals. Neth, a 24-year-old from the West Country, describes herself as a "panromantic asexual". Like all the asexual people I spoke to, Neth explains that she has known she was asexual since adolescence but only recently realised that there was a term for how she felt. Neth also identifies herself as "genderqueer", a general term used by people who don't identify themselves as men or women. "Sometimes I feel more like a girl and sometimes I don't at all. If we were all in some magical world, I'd love to be able to change the shape of my body to go along with those shifts, but, alas, that's a fantasy." She is currently single. Her previous relationship with a boyfriend ended some years ago, before she "came out" as asexual: "His desires and attractions were, well, different from my own, and I don't think he ever realised what was going on with me. There was some sexual stuff at the start: he wanted it and I was caught up in having a boyfriend. I remember feeling awkward afterwards. Having spent years not thinking about any of this, it was obvious I didn't really want sex. I ended up avoiding him a fair bit and it just fizzled out and we ended up as friends."

We know asexuality isn't celibacy, but it invariably raises a few knee-jerk questions: are you just repressed? Are you secretly gay? Were you abused?

Dr Lori Brotto, assistant professor in the Department of Obstetrics and Gynaecology at the University of British Columbia, is, alongside Dr Bogaert, one of the leading academics in the field of asexuality. But Brotto's findings raise more questions about asexuality than they answer. For example, her research shows there is no gender split; men and women are equally likely to be asexual. However, asexual men are much more likely to masturbate than asexual women; as likely, it would seem, as men with "normal" sex drives, suggesting that they are responding to a physical imperative. When Brotto conducted an experiment to measure the vaginal reactions of female participants to visual sexual stimulus, the physical reactions among asexual women were the same as that of women who report an otherwise "normal" sex drive. Brotto also says there is nothing to suggest that asexual people are any more or less likely to have suffered childhood abuse than anyone else.

Dr Bogaert's research suggests that a "fraternal birth effect" seemed to be a factor: asexuals are more likely to have older brothers. His findings have also established that "asexuals, like gay people, are more likely to be left-handed". But what does any of this mean in terms of understanding asexuality better? "If I had the funds, I'd commission brain-imagery studies to show how an asexual person processes sex. This would help lead us to other answers: is this hormone related? Is asexuality genetic?"

Brotto and Bogaert have each applied for funds, but as asexuality presents no danger in the way, for example, the Aids epidemic did, there is little interest in the funding further research.

In a long email exchange with Andrew, a 28-year-old asexual man from St Louis, Missouri, I find myself asking the kinds of questions that are, frankly, offensive. He had a deeply religious upbringing, and describes how bizarre the chastity doctrine passed on to him and his peers seemed to someone who didn't want to have sex anyway. So did your religious upbringing have anything to do with your asexuality, I ask. "Most of the 'mainstream' responses you get are, basically, attempts to explain away asexuality and to not have to take it seriously. It'll be a long time before we have any idea as to what causes asexuality, and I think that causation has little relevance to validity, " he writes back. I'm embarrassed. I would never ask a gay person whether their upbringing had made them gay, so why does it trip off the tongue when talking to an asexual person? Asexuals don't necessarily have an issue with being asexual, but they do with the assumption that it is "caused".

Andrew suggests I contact Mark Carrigan, a doctoral researcher at Warwick University. Carrigan disagrees with David Jay's theory that we are in the third phase of the asexuality movement: "I don't see how it's possible to say we're now at a stage where mainstream assumptions about asexuality are being changed while most of the population are only dimly aware of its existence."

Carrigan's theory is that the visibility of asexuality is a reaction to the postwar arrival of consumer consumption, sexual liberation and the pill. "Most of the asexual people that I speak to find that 'coming out' to their parents is hard but that their grandparents are actually very understanding." Is the way we respond to asexuals, then, partly a generational issue?

"I suspect it's only when sex becomes something public, visible and widely discussed that a lack of sexual attraction becomes problematic," says Corrigan. "While it remained a private thing, asexuality wasn't rendered an 'issue' for asexual individuals and there was no need to find a term and claim recognition for their identity."

Suzie King echoes Carrigan's ideas: "Anything that goes against the norm, and threatens the status quo, is to be ridiculed and got rid of. The reactions that asexual people have to deal with show how ill-educated, narrow-minded and not really 'open' about sex we really are."

Laura, 21, from Scotland, has known she was asexual from adolescence. "At school, all the other girls started getting crushes when we were about 13. I had no idea what they were talking about." At her job in a local bar, Laura is propositioned by customers regularly. "I've tried to explain a few times that I'm asexual but they just say, 'Well you've never had it with me, love!' so in the end it just seems easier not to talk about it at all."

For more information and advice visit platonicpartners.co.uk and asexuality.org. Some names have been changed