What do boys learn about when they learn about sex?

This summer's most striking image of male sexuality was not of some bronzed hunk on a beach. It was of 11-year-old Sean Stewart, shocked to discover he had fathered a child by 15-year-old Emma Webster. "I assumed it was a childish romance," said Sean's mother. "I wondered if they had held hands or cuddled but not in my wildest dreams did I imagine they were having sex."

The story raises in extreme form the problems parents face in introducing boys to an understanding of sex, especially now, when the media exposes children to images of sex long before they understand what it involves; boys, just as much as girls, can easily drift into sexual experiences with no real idea of what they are getting into.

This week, Miriam Stoppard, doctor, health guru and agony aunt, publishes Sex Ed, a book aimed at both male and female teenagers. " I believe in harm reduction," she says, "You can't expect children to be responsible, they will experiment and I believe that information discourages experimentation. Of course some children are embarrassed and if an adult is alarmist, this does not communicate a message. You can't force information but you can make it available to them and respect their privacy.

"It is good to mention that, for example, it is very normal to masturbate. Also, include feelings, values, emotions, love and fairness. That is where parents have the advantage over teachers. Feelings is what sex is about and they are not covered by school.

"Children don't come to you embarrassed, they are very natural and it would be odd if they weren't. And a child will remember if the questions are answered shiftily and then they won't come back."

The truth, as every man knows is that boys are much less well provided for. The caring mother will talk to her daughter when she begins to have periods. But for boys, there is no similar explicit mark of puberty that makes it impossible to avoid the subject. If their fathers or mothers do deal with sex, it is usually too late, when the boy has already reach the stage of being too embarrassed to talk to them about it. Sometimes parents will supply a book in the vain hope that this will deal with the problem. But report after report finds that many fathers completely avoid the issue: the days when dad took his lad off to a prostitute to learn a thing or two are long gone.

It is easy enough to see why learning about sex is harder for boys. Pubescent boys typically find it hard to talk about anything, never mind sex. And the task is left to men, many of whom cannot discuss sex even with their partners. In contrast, women talk about sex a lot and girls have dozens of magazines which explore sexual development.

A few books can be found aimed specifically at boys. Nick Fisher is author of Living with a Willie (Macmillan pounds 3.50), which goes from "the winkle years" through to "sex and your sausage". Fisher believes that it is almost impossible for teachers to provide good sex education. "A boy finds it hard to sit beside someone he has just done a geography lesson with and then start talking about sex with a teacher who normally takes history." Dr Stoppard agrees: "The classroom context feels too awkward, and almost precludes questions." There seems to be no escaping the need for parents to fill in the gaps.

Five tips for parents wanting to help their sons deal with sex.

1 Learn to talk to your own partner about sex. If you can't do that, you will never be able to speak easily to your child.

2 Listen to your son.

3 Start early. Don't wait until puberty when taboos are harder to break down.

4 Find some good books - if your son won't talk at least he can read something.

5 Choose a friend or relative who will also encourage your son to discuss sex if he finds it too difficult talk to you.

Sex Ed is published by Dorling Kindersley, priced pounds 5.99