How is Christopher Tony's nephew? Who of Chris' parents related to Tony and how?

Where does it say that? I went over the first 3 seasons three times over and never found a reference except that he's a "nephew".


"..Your youngest and strongest will fall by the sword.."

"...now you gotta speak more than one language to pull a heist..." Pudge Nichols

"...Never shall innocent blood be shed; yet the blood of the wicked shall flow like a river. The THREE shall spread their blackened wings and be the vengeaful striking hammer of God..."