its called ( trialia tekmainai) I'm not shure how to spell it? put its a compulsive disorder most pp who have it dont even realize their doing it same as someone who bites their nails stress can cause some one to pull even more when having this disorder.
Trichotillomania www.ncbi.nlm.nih.gov This site will tell you more about it. I would compare it to being obsessive/compulsive. Its never right to dog someone about it-don't you think they'd quit if they could?