This is Peter Hitchens's Mail on Sunday column

The mystery of sex education is that parents put up with it at all. It began about 50 years ago, on the pretext that it would reduce unmarried teen pregnancies and sexual diseases. Every time these problems got worse, the answer was more sex education, more explicit than before.

Since then, unmarried pregnancies have become pretty much normal, and sexual diseases – and the ‘use’ of pornography – are an epidemic.

It is only thanks to frantic free handouts of ‘morning after’ pills and an abortion massacre that the number of teenage mothers has finally begun to level off after decades in which it zoomed upwards across the graph paper.

In a normal, reasonable society, a failure as big as this would cause a change of mind. Not here.

If you try to question sex education, you are screamed at by fanatics. This is because it isn’t, and never has been, what it claims to be. Sex education is propaganda for the permissive society. It was invented by the communist George Lukacs, schools commissar during the insane Hungarian Soviet Republic in 1919, to debauch the morals of Christian schoolgirls.

It works by breaking taboos and by portraying actions as normal that would once have been seen as wrong. Last week we learned that the Government has officially endorsed material which says sex at 13, ‘for those of similar age and developmental ability’, is normal.

This is, no doubt, a point of view. In a free society, people are entitled to hold it, even if it is rather creepy. But do you want your child’s school to endorse it? And how does it square with our incessant frenzied panic about child sex abuse?

If we are so keen on the innocence of the young – and I very much think we should be – then surely this sort of radical propaganda is deeply dangerous. We do not give schools this huge power over the minds of the young for such a purpose.

How odd it is that we teach 13-year-olds to go forth and multiply, but can’t somehow teach them their times tables. Shouldn’t it be the other way round?