Do romeo and Juliet ever discover they are from feuding families?

It depends on what you mean by real. There really were two families called Montecchi and Capuletti who were opposed to one another because of being on opposite sides of the Italian conflict between the Guelfs and the Ghibbelines. However, only one of the families lived in Verona, and the story of Romeo and Juliet did not actually happen to them. So although they were real families and they did feud, their feud was not the "Romeo and Juliet family feud". Since the Romeo and Juliet story is a fiction, the feud is only real within the context of the story. In that sense, and in that sense only, the feud is as real as Romeo and Juliet's love.