Some time ago I read a book on the early days of Communist infiltration of American institutions. The author noted that many of the early members of the Communist Party in the USA were Jewish and he had what sounded to me like a rational explanation that relates to the issue at hand: Why are Jews so Liberal. The author's view was that historically the Jews have been a persecuted race/religion/ whatever. That knowledge is now buried deep in the genetic structure (so to speak) of Jews in general - they know their history. The attraction of a truly egalitarian society ala Marx/Communism was a direct result of this view of a persecuted race. The early Jewish Communists held the view, not entirely without reason, that Communism promised a society free of persecution - if everyone is equal than nobody will be singled out. As we know, that idea was entirely false. It didn't work out.
But the historical knowledge of the Jewish people remains and the idea that egalitarian socialism might relieve them of the threat of persecution remains. It is the source of Jewish Liberalism.
It puzzles me that every Jewish senator is a dependable vote for amnesty, and Jews are everywhere in the immigration system, fighting to let as many into the US as possible, and fighting to prevent deportations. I think their historic plight of being without a country for many centuries, and often expelled from various nations, makes them almost automatic open borders advocates, even when groups that hate them are ever increasing in numbers, and making the US a less safe and accepting place for them as has happened in parts of Europe.
There often seems to be a very self-destructive element to parts of Jewish liberalism.
It's worth noting that most Jews in the U.S. today can trace their ancestry to immigrants from Europe (particularly Eastern Europe) in the early decades of the 20th century. These folks came to the U.S. from places where totalitarian nanny-state governments were a way of life, and while they certainly fled for good reason the simple truth is that they brought many of these nanny-state expectations with them.