Their Jewishness is relevant because Jeannette the stereotypical Jewish parent obsessed with a kid going to an elite college, something none of her other average kids were able to do. Google stereotypes of Jewish mothers and the only missing there is Jeanette's picture. And of course, the trying to pass with a white last name, no Jewish person ever did that...right? Sorry, but yes, their Jewishness is as relevant as Christianity is for Anna Johnson. It's a big part of their identity and behaviours.