I used to bite my nails as a kid and then graduated to sort of trying to file/tear them down with my teeth if they were bugging me. Sounds weird but makes sense in my head okay? ;_;' So I don't technically bite my nails anymore but I still quite often have to deal with short nails because of my actions.
Since I started painting my nails fairly regularly, though, I've had way fewer problems because the polish keeps the nails from snagging/damaging so often and I'm so much less likely to mess them up when it'll mess up the polish too. :P