It’s dirty and disgusting. So why do we bite our nails?

I’ve been biting my nails even since I can remember. I do it automatically, without even realizing it: I’m focused on writing a story, and before I know it, my finger is in my mouth and I’m greedily chewing a nail or a cuticle. I hate that I bite my nails; it makes me feel ashamed, and I’ve tried quitting multiple times. So why do I keep doing it? The answer is more complicated than you’d think.
Scientists, in fact, are still trying to figure out exactly why people