It's a fair question. Jews have always played a part in civil rights and social issues particularly due to our own history of being persecuted. For many, I think they have a hard time separating themselves from that and looking at the bigger picture. Our history, our religion teachings, it's just tough for many Jews to understand that the liberal view is not always the best answer to solving many social issues. It just sounds better. In addition FDR and his New Deal was aimed at helping the poor. As Jews emigrated from Eastern Europe most were very poor and FDR appealed to them. Lastly, I think Republicans in those decades tended to be more uber religious christians and that may have scared off Jews escaping the holocaust etc. Ironically, Jews in America might be more tilted towards the left but Jews in other Countries are more center-right including Israel , UK, Australia and other European countries.
Im Jewish and ask myself the same question.
