I believe in a more rondabout plot: she's not the baby left to die in the woods, but her birth circunstances make them believe she is. So, in this case will have a ton load of unnecessary drama (their forbidden love, she being used as a pawn) to be used in the story. Will be necessary a lot of chapters until someone unveil the real truth, making the "real" love possible again, because they are meant to be together, and everybody has to accept. A incestuous plot would be rejected by the public, that's for sure. In my opinion, all this is a little bit too ridiculous, isn't it?