Becky Wahlstrom isn't a Jew, but she plays one on TV. As Grace Polk on CBS's "Joan of Arcadia," the blond Chicagoan looks refreshingly unlike your stereotypical Jewish character. Of course, Grace's character wasn't supposed to seem Jewish from the start. The contrary, politically outspoken, rebellious teenager in black has been packed with surprises since her character debuted in last year's first season. Recently, it came to light that her mother is an alcoholic. Toward the end of last year, it was revealed that her father was a rabbi and that, at age 16, she was finally giving in to his pleadings that she have a bat mitzvah. Tonight, then, is the big night. Grace will become a woman in the eyes of the Jewish community at 8 p.m. on Friday, Nov. 26.