Fischer's mother was, in fact, Jewish and he was raised in a Jewish neighborhood with Jewish friends. She was Regina Wender Fischer Pustan, a pediatrician who had, in the 1930s, briefly worked as a secretary to eventual Nobel Prizewinner Hermann J. Muller.

It was 'suspected' that she was actually a Soviet spy
and her mail had been read by feds, and her co-workers were interviewed, which often cost her employment.
- from an investigation in the Philadelphia Inquirer

In one broadcast chat while a 'fugitive' (he played Spassky in Yugoslavia despite the State Department forbidding him to play resulting in a warrent for his arrest) Fischer described himself as a victim of an international Jewish conspiracy.

A complex man and a briiliant chess player.