I know how you feel. A family member who I visit on a regular basis picks their nails and toenails and bites their nails. It is constant and never stops. The person does it even when eating and it makes me sick. I dread being with the person because of this. It is so unfortunate because the person knows that it drives me insane but does not seem to care and does it anyway. It is too sensitive to say anything as it would start a fight with the rest of the family. I don’t really have any suggestions but I feel your pain. Since your family member knows it bothers you and mine does as well, I don’t understand why they would not make an effort to stop the behavior.