I don't know if nail biting could be a repression mechanism for some. I too was a nail biter for as long as I could remember. Started when I was really young and after years and years of unsuccessful attempts to stop, I finally did kick that habit about 8 months ago. I think for me nail biting was more an anxiety manifestation more than anything else. Primarily it was a an unconscious activity. I usually wouldn't even realize I was doing it until it bugged someone else and they told me to stop. I did a lot of what Forest suggested in his post. I gauged my emotional state when I would find myself biting my nails and I looked for patterns. What I found was that I primarily bit my nails when I was reading and it didn't matter what I was reading - a book, a magazine, a billboard, even a computer screen at work. If my eyes were reading my nails were getting nibbled. The more I thought about it and followed the internal energy I realized it made perfect sense. When I was a child I loved to read. I could be in a room full of people and I was very content to sit in a corner alone and lose myself in the fantasy taking place inside the pages of a book. Unfortunately for me, my love for reading displeased my mother. It wasn't so much the activity itself that she had a problem with, but the solidarity of it. If there were other options (especially ones involving interacting with others) she preferred I not be reading. So, the result of that was that I was probably one of the only children who heard "would you put the damn book down already" rather than being told to "go read a book" like every other kid on the planet. I realized that even as an adult, the people pleaser in me was on high alert waiting to be reprimanded for displeasing someone with my reading. What finally worked for me was sitting down with a picture of myself about the age of 5 or so and talking to that little girl. I told her that it was ok if she wanted to read a book. There was much to learn inside every book and learning was a good thing. I also reminded her that Mom was not lurking around the corner in my house waiting to loudly demand that I put the damn book down and go play with my siblings. Once I convinced my inner child that it was safe to read, the nail biting stopped without even trying.