I come from a family of nail biters, in particular, my dad bit his down to the nubs..... I know yuck and a niece of mine and brother did the same.. however, my mother never bit hers.. That said, when I was younger, especially VERY young and into my teens and early 20s was when my nailbiting was at its worst and not so coincidental when my life was the most stressful.. I had a vicious habit... while I definitely think stress plays a role which can then turn into habit, I also think in part, it's a learned behavior.. I have also read that it's akin to that of when people pull their hair out by the cuticles, piece by piece which could be a result of an ocd disorder..
scroll ahead to me now being 50.. while I don't bite my nails, If nervous, I might pick at a hangnail... However, I have since discovered that a lack of vitamins/minerals in the body may contribute to a person biting their nails, it's on the lines of having pica... Recently I was diagnosed with anemia and since taking my liquid iron.. what a HUGE difference in my not wanting to pick at my fingers. I am not cured completely, but.... there is definitely a difference in not only my not picking at my fingers but also my cravings... thing is, when I would get cravings, in my case for dry pasta, I would become nervous and with that so would go the picking at my fingers.. since taking iron, WOW............. my cravings are gone by 80% at least.. and the picking at hang nails has dropped off significantly. .now some might say, what the H does iron have to do with it.. well I believe it all relates in part to our body chemistry... you aren't just picking at your fingers because it's a habit and even if it is.. it began for a reason.. I believe now I have been deficient in certain vitamins and minerals for sometime.... if you don't believe me.. check out the net and look at nailbiting, pica and other related things.. as you delve into it, you ll probably begin to see the correlation ... do you have insurance and if so, if you do a physical, why not ask the doc to do a blood and hormone count..
what also contributed to my nailbiting in my case was when I began perimenapause.. in that as my estrogen dropped, my cortisol (stress hormone) level rose and that caused me ti become even more anxious.
again, it's all about body chemistry.. could be something else is going on on the inside.. my husband used to think I could just stop the habit, but no matter how hard I tried I failed...... again, it wasn't until I began the iron that I was able to stop the nail picking.... and stop the dry pasta cravings.. I really think it's something worth getting checked out. oh and don't be surprised if the doctor laughs and thinks you are crazy (so many of them don't study much nutrition) so if you tell them you think it's hormonal, nutritional based, they might ignore you. but get the blood/hormone tests anyway. it's your body not theirs.. when I told my doctor, I think I have pica.. she smirked.. turns out.. I was anemic and one of the big things that can happen are weird cravings...... so she was wrong for smirking..
good luck.. keep us posted..