Nail biting

Dear Mr. Alice:

Why is it that so many people bite their nails?

-- Michelle, the net

It's been studied scientifically, so there are a few reliable things known about onychophagia. Unfortunately, "why" isn't one of them. Every time you sit down to a dinner for four, consider that one of you probably had a fingernail hors d'oeuvre sometime that day. (Actually, most nail biters don't swallow, they spit when they're through doing whatever they do with the torn-off nail.) One out of four adults (regardless of sex, national origin, IQ, mental stability) is a nail-biter. And one out of three nail-biters has the inclination, and apparently the agility, to bite his or her toenails. This is science, folks. I don�t make this stuff up.

Nail biting usually begins between ages five and six, though the peak harvesting years are, no surprise, adolescence. Studies suggest a predisposition to nail biting is inherited, though nobody's ID'd a nail-biting gene. Many investigators believe the habit's a way to discharge tension, anxiety, or anger, but nobody's actually proved that. Part of the problem of finding out "why" is the likelihood that nail biting begins as a response to some stimulus but persists into adulthood purely as a long-term habit, years after the original stimulus is gone.