I read this thing though, apparently it's a myth that he was Jewish. I just posted this story in another thread read it though, not sure if anyone'll get it though:
Contrary to popular opinion, one of the more popular heavyweights, Max Baer, was not Jewish, boxing historians say. Lawrence S. Ritter, author of "East Side, West Side," a chronicle of forgotten sporting clubs in New York, tells in the book of a time when Baer was in a gym hitting a heavy bag on Yom Kippur.
"What are you doing?" a reporter asked Baer, confused.
"Getting ready to fight Primo Carnera," he said.
"What about Yom Kippur?"
"I'll fight him next!" Baer replied