This is about a book series I read in the 80's or 90's. The books were about brothers in either Georgia or North Carolina. There was some sort of metal-sculpting theme thrown in. One brother was somehow twice as powerful because his uncle was his dad. He had a crutch that he affixed miniature figures to. The family was well off but the brother with the crutch was not raised as part of the family until his mid to late teens.
I've put this on a fantasy site because there was magic involved. It was modern, set in the south either Georgia or North Carolina. For their magic/powers to work they had to be completely "whole" when they were supposed to come into their magic. I believe the brother that didn't know he was related was a swimmer and injured himself. As it turned out he hurt himself just after the change.