Joan Smith: I see, it's all our fault then, boys

The headlines are unequivocal: new research published in a reputable scientific journal has shown that the female orgasm is "all in the genes" and that "genes determine [a] woman's ability to have an orgasm". According to The Guardian, the study is also "the most compelling evidence so far that the female orgasm has a biological role", which is apparently to weed out men who are useless in bed.

I had to scratch my head over this for a moment, trying to spot the connection, and, to be fair, it isn't actually in the study. It comes from a throwaway remark by the man who led the research, Professor Tim Spector of St Thomas' Hospital, London, who suggested in interviews that the fact that women take longer to come allows them to "assess men in their sexual powers or ability which... is a marker for whether they are likely to be a long-term mate".

I'm sorry? There's no obvious reason why a man who is good in bed should be a better prospect as a long-term partner. Even more worrying is the speed with which this controversial piece of research (I'll come to that in a moment) has been accepted as gospel truth. In no time at all, the blame game was under way, with an internet news service telling women who have problems reaching orgasm to "blame your mum" - not your husband or lover, but your genetic inheritance.

When I spoke to Dr Petra Boynton, a London-based sex researcher, she was equally puzzled by the study's reception. "Journalists usually ask lots of questions but, on this occasion, no one seems to have asked very much at all," she told me. "The problems with the research aren't too difficult to spot if you actually read the paper or talk to a sex researcher."

In fact, big assumptions have been made on the basis of two imprecisely worded questions about sex in a postal survey of twins that investigated the role of genes across a much larger area, from hypertension to musical ability.

The sex questions asked women how frequently they experienced orgasm during intercourse - now there's a word I haven't heard for a while - and masturbation. From the responses, the researchers concluded that the ability to reach orgasm varies widely between women, and that between 34 and 45 per cent of this variation is due to genetics rather than culture, upbringing, religion or race. But the findings are less impressive when you realise that significant words in the questions (such as "overall" and "frequently") were not defined, while the researchers seem to have regarded not having an orgasm during penetrative sex as evidence of "orgasmic dysfunction" - an attitude I thought went out with the ark.

What cries out at me from this research is the way in which it lets men off the hook, even if I am generous and assume that clod-hopping lovers are included in "cultural" reasons for women not having orgasms. Like other studies that come under the heading of evolutionary psychology, it also has the effect of disempowering women. I remember the excitement with which my generation discovered that a great deal of what we had been told about sex was actually sexist rubbish, including Freud's assertion that "mature" orgasms originate in the vagina rather than the clitoris.

Now we're expected to believe we were wrong all along and our sexual choices are largely determined by genetic factors; what we're really trying to do is get access to high-quality sperm and men who are good providers, regardless of what's going on in our pretty little heads.

Professor Spector has even invented a new category from his research, women who have orgasms "too easily" - the sluts! (They're not very good mate selectors, apparently, having a tendency to be satisfied with "poor quality men".)

Dr Boynton detects "a subtext in all this around women needing powerful men to make them safe. It's the alpha male that wins through". She's right and it accounts for all those uncritical headlines. Biology may not be destiny, but an awful lot of people would like to believe it is.