nail biting is a nervous habit. i bit my nails until i was 19 and then off and on thru my life. what made me stop was sheer will power. you have to want to stop a habit. i used to get my nails manicured. not with fake nails but with just my plain chewed off nails. i would get a manicure once a week. i would try not to bite them in between. when my fingers didnt hurt anymore and i actually had nails it was easy to stop. i don't know if your brother would be willing to have a manicure but it is not unusual for professional men to have them. i keep my nails short now but i don't bite them. if your brother is going thru some rough times i doubt if you can get him to quit. but not having sore nails was a real inscentive for me.