How were TR and Franklin Roosevelt related?

Answer 1

I think they were second or third cousins. TR was not Jewish though, however FDR was (from the female, Delano, side of his family.) Explains him not taking Hitler's side.

Answer 2

From what I understand, FDR married Theodore Roosevelt's niece, Eleanore Roosevelt, who was also his own fifth cousin, once removed. The whole family tree is complicated, and so FDR and TR are distant cousins, and FDR is TR's nephew by marriage.