I bit my nails most of my life (I'm 62) until I had a lot of therapy for my anxiety and until after my stepmother died, etc. Can you think back and see if you can see what happened six years ago that you started?

It is good you are paying attention to "when" you bite them. I bite mine now (occasionally, now they are usually "acceptable" to me) most often when I am reading. I have a history with my books; I read for emotional education as much as anything else and respond deeply to the situations the characters in my novels are responding to? Too, sometimes I will be reading/watching TV and drinking at the same time and that can lower my inhibitions further.

If I could do it all again, I would not bother being upset about my nails and whether I bit them or not, I would accept that anxiety symptom and work harder on my self esteem/knowledge and the anxiety itself instead of diverting and/or adding anxiety and energy to biting/not biting my nails and what others thought.

It is a habit though too. I read where one person put nail files/grooming equipment all over, each place she sat, etc. and substituted working on her nails to biting them. I think you just have to become more aware of when you are biting them and decide to do something else like that.