I've been biting my nails since I was a little boy. When i watch sports I bite my nails. When I played sports in high school I bit my nails. Alot of the time I don't even realize I'm doing it. This may be gross, but I even clip my toe nails, and eat them. When I was younger I'd eat the skin off of the bottom of my feet. Sometimes to the point where they would bleed. I still do this sometimes, but I have to use a nail clipper sometimes. I don't know how to stop, so it will probably continue until I find something to help me stop.