I have heard before that none of the (at least, the prominent) second-generation Frankfurt School were Jewish—including Habermas. Actually, he is probably the only well known one who isn't. Another major one of Jewish extraction is the Freudian psychologist Erich Fromm, who supposedly had a big part to play in the early first-generation, but was practically ostracized and written out of its history after having fell afoul of its major figures.

Only the first and second generations had any real influence. The third and fourth generations aren't that far off of being unknown, and are mostly liberal-progressive rather than radical.