I think he's also the grandson of a famous American Commie.
The grandson of Norman Thomas
"Norman Mattoon Thomas, b. Marion, Ohio, Nov. 20, 1884, d. Dec. 19, 1968, was six times an unsuccessful Socialist party candidate for president of the United States between 1928 and 1948. A Presbyterian minister in East Harlem's slums, he became a pacifist and opposed American entry into World War I. In 1917 he helped found what became the American Civil Liberties Union. Thomas joined the Socialist party in 1918 and became its leader in 1926. Espousing a moderate, non-Marxist brand of socialism, he failed (except in the 1932 election) to halt the decline of his party."
Continued at link. (And I've always wondered just how much Evan Thomas takes after his grandfather...)