I think (but I'm not sure) that the original question/point was: 'is it only Jews who can tell only Jewish jokes' (or maybe it was 'is it only Jews who have to make every joke a Jewish joke') 'or do other groups do the same thing?'. {Parse THAT punctuation. pedants!}

IMHO, most people who aren't seriously into insulting others will make a joke that seems to require a racial/ethnic/religious/distinguishing characteristic identity into one that doesn't gratuitously insult somebody else, and the best way to do that is to tell it on your own group. On the other hand, people like me who are multi-ethnic and non-religious are somewhat handicapped in that sense.