It would be strange to assume uncritically that Nobel prizes were given out in a way which was completely unbiased. For example, it is at least highly plausible that there are biases on the basis of nationality, connections, school background and other things which have nothing to do with merit, ethnicity OR culture as such. So it seems strange to me to suggest that it must be some aspect of Jewishness that determines this difference.
I'm actually not assuming that - I tried to write something to that effect, but I wasn't pleased with what I wrote. Take my comment with the pre-condition that if we're going to assume it has something to do with Jews themselves, it need not be attributed to genetics.
