He's definitely is a Riccobono and in the suicide letter it even confirms it (although it could be another johnny I doubt it) and I believe in the book the author was able to verify him being one or having a name change. The guy is so rich and the story is so extensive I don't think he'd make up baseline facts like those up. Apparently his father was a complete and utter psychopath who told him "if you are going to do evil, make sure you do it as evil as you can." or something like that.