Is there a logical or psychological reason why people bite their nails?

or what?Is there a logical or psychological reason why people bite their nails?
In a nervous or stressful situation one can be conditioned to act out a habit during that situation in order to bring them ease. Thus the impulse to bite your nails may become a regular and subconscious activity during any situation due to the closure it brings(although that doesn't imply you're consciously aware of this closure) Other habits are picked up this way i.e. grinding teeth, picking skin, biting of lips/gums ect. These habits can become very obsessive and can go from being done when under stress to a regular activity in your everyday whether your bored, watching TV, talking, ect.Is there a logical or psychological reason why people bite their nails?
Its a habit with some people. I sometimes bite my nails not out of nervousness but out of impulse and at times I'm not conscious of it. Its only thinking back on moments I am aware of it now then at the time so the psychological part of it is when the sub-consciousness comes into play when performing such habits.
No, it is just a bad habit that gets developed by the brain. Some people do it all the time. Others just when their nervous.
If you understand the psychology of the person who bites his nails, then all makes sense so there is logic like the person is stressed or has a very bad habit
It has been said that people who bite their nails have a very short temper.
i do it for comfort - that and i have a calcium deficiency so they don't grow past a certain point anyway...