how do I get my 4 year old to stop biting his nails? his dad had the same bad habit as a kid. biting his nails, sweaters, chewing on straws. it's so fucken annoying. I've talked to him nicely, I've punished, even tho it doesn't seem right. he once said it was bc he was hungry when his sister was first born. I thought ok I probably have been neglecting him but he eats til he's full now and still does it. nobody yells at him to the point of scaring him or making him nervous. idk what else to do.