The connection between peeling a potato, sex and the morality of our young may seem obscure. But it was in just this occupation that my middle son (then aged 15, going on 16) announced that he was sleeping with his girlfriend. I continued to peel the potato, trying hard not to retort:

“Well, I hope you are taking precautions.” By the time the potato had become chip-sized (I was going to roast them) and with my mind reeling at his lost innocence, I finally managed to compose a suitable reply. It was to do with what he thought was right for him and his girlfriend. The precaution bit came later when we had made suitable eye contact.

So I was not particularly shocked by the recent news that a 12-year-old girl in Yorkshire had become pregnant by her 14-year-old boyfriend. It’s sad they will lose their young independent lives.

But what I do question is the Government’s knee-jerk reaction, with Tony Blair calling for society to adopt a “new moral purpose” and David Blunkett’s announcing that guidance on “relationships” and the value of marriage will be introduced into the national curriculum. For votes or value?

Sex play between boys and girls happens - and has always happened - in primary schools. Studies show that between 35 to 40 per cent of children will admit to having had heterosexual sex play between the ages of seven and 11. The step to intercourse is not a magnum leap. And this step has more to do with hormones, basic biological instincts and adolescent rebellion and curiosity than any ideas about love, sex and relationships.

Will teaching our young children the value of relationships, the importance of marriage and the family unit prepare them for the time of raging hormones and adolescent rebellion against all parental and adult authority? We may educate them about conception, contraception and sexually transmitted diseases, but how effective can we be beyond that?

In fact, in the face of numerous population studies there is still no consensus about whether parents or schools are most effective in providing sex education, or whether handing out free contraception from an early age increases or decreases sexual activity among adolescents. Is there any evidence that trying to teach a class of seven year olds about relationships, love and marriage will have any effect on them and their subsequent sexual proclivities?

In inner city comprehensives, it is likely that about 50 per cent of children will belong to a single-parent family or a family “unit” in which a divorced parent has remarried. Other children will come from unhappily married two-parent families; yet others may come from a happy, unmarried two-parent family. These diverse backgrounds makes it almost impossible to cater for all their needs when teaching them, in the classroom, about the meaning of love and the importance of the family unit.

In 1989, Margaret Thatcher said there was no such thing as society, “only family life”. In a later interview published in the Daily Mail, she argued that: “The family - is the most important thing not only in your personal life but in the life of any community - (it) is the unit on which the whole nation is built.”

Her sentiments regarding the ideology of the family - Mum, Dad and 2.7 children who should all love one another - have been echoed in subsequent government propaganda. But are politicians not aware that there is no conclusive proof that the nuclear family is necessarily the most successful form of child-rearing? Nor indeed the most common. One strong parent can provide more efficient and loving care than two weak warring parents.

Of course 12-year-olds should not become pregnant or have sexual relationships at such an early age - and they need to be informed about the risks of sex. But before the Government throws more money at sex education, it should consider how our society is naturally evolving, and whether in a country in which one in three (or more) marriages ends in divorce there is any value, or indeed effectiveness, in introducing lessons on marriage and relationships to primary schools.

Saffron Davies is a senior lecturer in physiology in a London medical school