VENLO, Netherlands - Do you find your fingers drifting into your mouth when you're nervous, anxious or just bored? Are your nails chewed to splinters or your cuticles gnawed to bleeding pulp? Nail biting is more than a bad habit. Doctors say it is one of the most common symptoms of stress or of an obsessive-compulsive disorder, especially for teenagers or younger children, and can lead to disfigurement and serious infection. Alain-Raymond van Abbe, a former health industry and cosmetics promoter, estimates the world's pathological nail biters number 600 million or more. He saw that onychophagy was so widespread that...