It can't be ALL genetic.. A lot of it is probably environmental. There are too many fish that come from breeders perfectly fine and develop tail biting in their new tanks. I have one who ripped his tail to several thin shreds (from a HM) and after trying everything to fix it, all it took was a brighter light for his tank. He doesn't bite at all anymore.
If you want to help his tail heal, IAL works wonders, but good, clean, clear water is the best medicine. Clean his tank, check all of his decorations for dangers (Look for something his tail could be getting stuck on or between) and keep him well fed. And maybe change his light. He could be seeing his reflection, and a brighter light would help that. Or invest in an aquarium background paper, the patterns keep him from seeing himself properly. Maybe make your own?