If Han Solo and Rey were Padme and Anakin's first children, it would mean that the Skywalker family would have had an entirely different destiny. Han and Rey would have grown up together as siblings and been trained in the Force by their parents. This would have likely impacted their paths in life and perhaps have meant that they would not have gone down the same dark paths as their parents. The result could have been an entirely different Star Wars universe, with possibilities that are hard to imagine.