H.F.
I just asked my pediatrician about this last week because my son bites his nails. I bit my nails all my life (off and on as an adult) and it makes me cringe to see my own son do it because of how much I despise it in myself. The pediatrician didn't seem to make it a big deal but he said I should redirect and give him other things to put in his mouth such as sugarless gum or a sugarless lollipop. Now if I can just teach my 5 year old how to chew gum instead of swallowing it...