Rubinstein was born in Pittsburgh, Pennsylvania, on May 28, 1933, to Jewish immigrant parents from Poland, Dolores and George Rubinstein. She was the youngest of three children and the only short-statured person in her family (Zelda has been incorrectly referred to as a dwarf). Rubinstein did not become comfortable with her short stature until she was an adult. In a 1992 interview with the Chicago Sun-Times, Rubinstein told the newspaper that she "had a rough childhood, [but] I became very verbally facile