I would like Braniac and Zod with Luthor in the background. Do we really know for sure that Jason is his son? Jason has pretty bad allergies and asthma so when Lex is holding the Kryptonite near him, he could just look sick because of stress which can trigger asthmatic reactions. We see the piano fly across the room, but it is obvious that Jason is intentionally off-screen when this happens. Also, when he goes to the locked steel door, we think he is just going to break the lock, but again the direction is very intentional about stopping him from doing this. Why the piano flew across the room for any other reason is something for which I just don't have an explanation, but if he isn't actually Kal-El's son, then I'm sure the writer's will have an explanation.