He's Our Fault Too!

It's not enough that Christopher Hitchens is a pompously arrogant self-righteous atheist who approaches his passion of denigrating those who disagree with him with an ironically religious fervour.  No, he has to be Jewish al pi halacha too!
For the first forty-odd years of my life I had thought of myself as English, latterly with ambitions to become an Anglo-American. This national self-definition underwent an interesting change as a consequence of my maternal grandmother’s outliving both of my parents. Yvonne took her own life at a distressingly young age. My father’s robust health began to fail him in his late seventies and he died in late 1987. My brother, Peter, in the meantime, had become engaged to a Jewish girl and had taken her to meet “Dodo” — old Mrs. Dorothy Hickman — our only surviving grandparent. Later, and after she’d congratulated him on his choice, she rather disconcerted Peter by saying: “She’s Jewish, isn’t she?” He had agreed that this was the case and then she’d disconcerted him even further by saying, “Well, I’ve got something to tell you. So are you.”
These stories always have one further detail not presented in the article.  Which famous rabbi is he descended from?  There's always one!