At 21, Andy Holland is happy, easy-going and interested in the same things as most university students. With one notable exception: Holland is not attracted to women, or to men. In fact, he has no desire to have sex. And in this, he is not as unusual as we might assume.

The first crush that Tessa Barratt had was on a Transformers toy called Rat Trap. “He was my first heart throb,” she says. The shelves in her bedroom are lined with models of Transformers. Playing with them now, laughs as she admits, “I don’t know how I fell in love with a rat.”

Barratt is now 22. But she’s not that much closer to having what most people would consider a normal, loving relationship: she’s still a virgin.

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“It’s hard to imagine what would push me to having sex. I’m not afraid of sex, it’s just not something I want to do. That’s probably why I delve into the world of science fiction and Transformers, where sex isn’t an issue at all.”

Barratt calls herself “asexual”, and says she’s very different to the many people who decide to abstain from sex for religious or moral reasons. “Celibacy is a choice, asexuality is an orientation. It’s not something you choose to be, it’s something you’re born as.”

It’s not easy to understand someone who claims to feel no sexual attraction towards other people. For most of us, sex is part of what makes us tick and sexuality informs so many of our decisions.

As Barratt recognises: “Some people find the concept of asexuality incredibly difficult to grasp. They don’t understand how you can be human and not want sex.”

And it all gets even harder to understand when you get on to the subject of masturbation. While filming a documentary for the BBC about asexuality, the first question I would be asked by “normal” people was: do asexuals masturbate? A lot of asexuals are annoyed by this apparently unnecessary intrusion into their private habits. But the truth is, the question gets straight to the heart of what makes an asexual tick. Because the answer, often, is yes.

Many asexuals have a sex drive, and many of them masturbate. But what makes them different is that their libido is dissociated from sexual attraction. Having a sex drive doesn’t translate into wanting sex. Put simply, there can be a sex drive, but not a drive towards anyone. “I can still feel sexual arousal,” says Barratt, “but I never want to act upon it.”

As this is so hard for the rest of us to understand. It might be easy to dismiss Barratt as frigid or afraid of sex – and many people do. “I get told I’m repressed, that I’m psychologically damaged, that it’s something to do with my history, that I’ve been abused. I’ve had people make out there’s something wrong with me, as if it’s a physical or psychological ailment.”

And the trouble is, as Barratt acknowledges, the banner of asexuality is an attractive hiding place for those who are repressing their sexuality – perhaps because of latent homosexuality, or a phobia of sex, or a childhood trauma. “I think there are some people who identify themselves as asexual who have a fear of sex, who may have had something traumatic in their past that’s put them off. I’m not denying that they may make up a proportion of the asexual population, but I do think there’s many who are also physiologically different, wired not to be attracted to other people.”

One asexual who certainly can’t be accused of being afraid of sex is Holland. And that’s because he’s tried it. Now a student at Warwick University, having got through his teens with no interest in sex, he then found himself in a comfortable relationship, aged 20. He was curious to see what sex would be like, so he decided to give it a go. He thought that trying it might kick his hormones into gear. “I thought some hidden sexuality might blossom, but it just wasn’t something that I was driven to do like she was.” After several months together, Holland split up with his girlfriend, partly because of the difference in sexual appetites.

Holland says that sex was “quite fun, quite enjoyable”, but crucially, he has no drive to go out and do it again. “If it happens it happens. I enjoy golf but if I never play it again, I don’t care.”

It’s so unusual – especially for a man – to have a complete lack of interest in sex, that while we were filming the documentary, Holland decided to see a GP, to make sure that there was nothing physically wrong with him. “It’s quite important for an asexual to check that there’s no underlying cause, because lots of people will think if I’m not interested in sex there’s a problem. It will help me feel more secure in my asexuality.”

With a lack of facial hair as well as no desire for sex, Holland wanted to make sure that low testosterone wasn’t a factor in his asexuality. Dr David Edwards runs a male sexual health clinic in Chipping Norton, Oxfordshire. One of the first things he wanted to establish was whether Holland might be depressed. Depression, and also anti-depressants, can often dampen libido. But it would be hard to find someone with a more cheerful and laid-back disposition than Holland.

Happy that there were no obvious psychological issues that could be contributing to Holland’s asexuality, Dr Edwards examined the blood test results. They were all totally normal – including his testosterone levels. As Dr Edwards told him: “I don’t think there’s anything I can find that may be a cause or factor in this. You may find things vary from year to year, but maybe not.”

Dr Edwards added: “It’s understandable that someone may have a libido but have no urge for sex. It is not an unusual thing. Some people are very far down one tangent.”

There are more people at the end of that tangent than people might imagine. A survey carried out in 1994 found that 1.05 per cent of respondents had “never felt sexually attracted to anyone at all”. In fact, more than 50 years ago, pioneering sex researcher Alfred Kinsey seemed to be aware of asexuality. He devised a scale of sexual orientation, in which subjects ranged from a score of 0 (completely homosexual) to 6 (completely heterosexual). But he labelled 1.5 per cent of adult males as “X” – neither homosexual nor heterosexual, nor anything in between. They were simply uninterested in sex.

For a long time, Kinsey’s Xs have remained hidden, but with the sexual revolution continuing at pace, asexuals are beginning to speak out. As the pressure to enjoy an active sex life is greatest on the young, many of the most vocal asexuals are in their twenties, like Barratt and Holland. But that doesn’t mean that older people can’t be asexual. As Dr Edwards notes: “Asexuality is not just a situation that affects the young adult – it can extend into older age groups, although they may not be so obvious.”

With sex being arguably the world’s favourite pastime, asexuals face an uphill struggle for recognition. It’s a testament to how sexualised our society is, that we accept almost any sort of sexual predilection, but when it comes to someone getting no sexual kicks at all, we’re at a loss as to how to understand it. We find it perfectly believable – if a little odd – that someone might want to have sex while wearing an asphyxiating latex mask, or while being whipped or spanked. But the idea that someone should deviate so far from the norm as to not want sex at all is almost incomprehensible. Most of us instinctively feel that there must be some sort of mental or physical problem, something that could be cured. We want to know why they’re like this.

But isn’t that how people thought about homosexuality 100 years ago, that they could pinpoint the reason as to why it existed? Little boys not playing with enough toy guns, little girls not having enough dolls? Now it’s much more simple – we just accept it’s the way some people are.

Perhaps it’s time to view asexuality with the same open-mindedness. Those with exceptionally high sex drives, who could be said to be at the opposite end of a spectrum from asexuals, are accepted – even implicitly admired. As Dr Edwards says: “The feeling of not being sexually attracted to anyone is part of a spectrum, and can affect men and women. It’s part of society’s rich tapestry of life.”

Olly Bootle is the producer/direcor of ‘Natalie Cassidy’s Real Britain: Sex’, which will broadcast on Thursday 19 March at 8pm on BBC3

Not in the mood: The facts

* According to Kinsey’s ‘Sexual Behavior in the Human Male’, 1.5 per cent of the adult male population exhibits “no socio-sexual contacts or reactions”.

* In ‘Sexual Behavior in the Human Female’, Kinsey argued that up to 19 per cent of the unmarried female population exhibited asexual behaviour or reactions.

* A study in the US found that 33.57 per cent of asexuals have problems with self-esteem.

* In 1994, a British study found that 1 per cent of people had never felt any sexual attraction to another person. The same study found that a larger proportion of women than men are asexual.

* In 1982, a survey of ‘Playboy’ magazine readers found that 2 per cent of respondents were asexual.

* Possible causes of asexuality include genetic predisposition, hormonal imbalance or childhood experiences.

* The largest asexuality group on Facebook has 585 members.

Leo Hornak