Nail-biters will always just need to clean up this last irritating bit of nail that's poking up, and we'll stop after that. The only thing that will make us stop, says Frankish, is if we find something more important or another way of relieving the anxiety "Keep children's hands busy," she advises. Her theory on nail-biting is that people do it because they lack a certain mineral in their body "Rubbish," says Samantha Sweet from Creative Nail Design. "A child will be anxious, chew their nails, find themselves less anxious and then make the connection between nail chewing and relief." It's what psychologists call "safety-making behaviour".

If you can't make the whole world safe, you'll make your world safe.Psychiatrists must have a field day analysing the hands of American Lee Redmond. She pops up on my children's favourite page of the Guinness World Records. Next to the heaviest twins and the man with the longest tongue sits the woman whose fingernails reach a combined length of 24 feet 7 inches She displays her hands like an armoury of exotic swords She hasn't cut them since 1979. She says that if a bomb went off, she's been told she could go into a shelter and live off her fingernails. It's a horrible habit and I've done it for as long as I can remember. I can live with the vice, and have learned to conceal it, but now two of my children have become nail-biters I can't bear to see them do it.

Ben, who is 12, will be racing down the football pitch chasing the ball. Seconds later, when he's not directly involved in the action, his hand reaches for his mouth. "Take your hand out of your mouth," I yell from the sidelines, while other parents are shouting, "Oi, ref" When he watches television he starts to nibble. So, too, does his brother, whose fingernails I have never had to cut. Why have I bred a pair of cannibals? Cannibalism is what it is.