How is Christopher Tony's nephew? He is not Janice's or Barbara's kid. Unless he is on Carmela's side of the family but it seems Christopher is alot closer to Tony then Carmela.

He's not really Tony's nephew. Christopher is the son of Carmela's cousin.

Christopher's parents are Joanne and Richard "Dickie" Moltisanti. Dickie and Carmela were cousins, thus Christopher is Carmela's second cousin. Although Tony often refers to Chris as Carm's nephew.

Actually, Christopher is Carm's first cousin once removed. Second cousins are people whose common ancestor are their great-grandparents. Carm's grandparents are Christopher's great-grandparents, so they are first cousins once removed.

It sounds pretty confusing, but I looked it up on the web once, because my friends and I had a disagreement on what a second cousin is.

I wondered if I'd mess this up somehow. I was going by the Wernick Family Tree on HBO. It list Chris as "second cousin to Carmela Soprano"
???? You're right that this "second cousin" stuff does get confusing.