My dad always bites his nails, and I picked up the habit as a young kid from him. The only problem is that I have a lower pain tolerance than him. So while he can handle the pain of the biting, my fingers always end up wrapped in bandages. Now to segue away from the mail biting (although some of my fingers are currently sore from that), there's a good chance i might have an oral fixation.
I say that because I always seem to wind up biting my nails, eating persistently all throughout the day (unless i'm at school or food isn't within my field of vision), etc. But even if i have an oral fixation, i like watching things change or diminish as I eat, I think. Because those chewing toys usually left me cold as a kid. They were hard and didn't have any give. Food is a thing which you can (to be metaphorical here) "do damage to." Same thing with nails. It's odd, but I like actually seeing results when I do things (hence why i bite my nails instead of chewing on safer things).
