Not entirely a joke. There is a historical connection between the small-town/rural Jews of the Czarist Empire, which is the basis for the musical/film "Fiddler on the Roof," and the adoption of leftist/socialist politics which were transplanted to the US by Jewish immigrants from that time frame and that part of the world. The irrational part of it is that a lot of that mentality still persists today, even though leftist ideology and policy has run counter to Jewish well-being and even survival in the US, Israel, and around the world for decades.