This is a video from the recent Conversation With Mark Hammil event at Disney's Star Wars Weekends in which Mark Hammil playing The Joker tells Mark Hammil playing Luke Skywalker that he's his father. Could you imagine if The Joker were your dad? There would literally be a zero percent chance of you not turning out severely psychologically disordered. And Harley Quinn? All your friends will ever talk about is how your mom gives them the most insane, long-lasting boners. Nobody should have to grow up like that.
Keep going for the video, as well as a much longer one of the entire interview.
Thanks to Stephanie A and jorb, who agree if you had to choose a dad from the Batman universe, almost anybody is probably better than Thomas Wayne.