There's no way to shield children from pornography You might argue that this could have a counter-productive effect - encouraging them to seek out dark corners of the internet that they would not otherwise have been aware of. But the sorry truth is, there is scarcely a 10-year-old left in the western world who doesn't know what porn is, and where to find it. If you find this hard to believe, consider the statistics. Seventy-five per cent of school-age children have their own computer, and 90 per cent own a smartphone. The average age at which boys first view internet porn - average, take note - is 11.5. By the age of 16, almost a third of boys and girls say they access pornographic images on their mobile phones several times a month. It's not just the quantity that matters, but the quality. This is not smut as you might fondly remember it from the top shelf: all soft-focus lingerie and come-hither glances. It is an altogether darker phenomenon. The vast majority of internet porn now takes its cue from the so-called "gonzo" genre: hard-core, dehumanising, often violent sex in which women are routinely debased and insulted. Like it or not - and I most definitely don't - this is how modern children learn about sex. By all means switch on the parental controls; but however carefully you monitor the technology in your home, your children will absorb the gonzo aesthetic by cultural osmosis. The evidence is that teenagers increasingly feel under pressure to ape the behaviour of porn stars. Girls as young as 12 are getting bikini waxes - not least because boys expect it. Sociologists report a rise in the more violent sexual acts, with predictably unhappy results. One in three 16 to 24-year-olds say that porn has adversely affected their relationships. I don't want my sons to grow up thinking they have to be macho and rough, or my daughter miserably feigning submissiveness. But they won't know better unless somebody enlightens them. It is up to us parents - and, to a lesser extent, teachers - to provide the countervailing influence; to make sure our children understand that pornography is fiction. Don't kid yourself that your child is too young to need "the talk." A friend of mine kept putting it off on the grounds that she didn't want to shatter her nine-year-old son's innocence. Then she discovered that he had been surfing granny porn on the family computer. My own children are all under five, but already I am trying to imprint on them, like newly hatched goslings, a more normal image of the female form. Like my own parents, I intend to keep striding around the house naked - and decidedly imperfect - until my children start rolling their eyes and begging me to desist. When they ask me how babies are made, (which they already do), I try to answer honestly, without blushing, so that we get into the habit of talking easily about sex. It sounds suspiciously Nordic, I know - and there are some parents for whom such conversations are just impossibly foreign. So it falls to teachers to go where those parents fear to tread. Increasingly, sex education is an act of mercy. Children need to learn the truth about sex - or they will be educated by liars.