Didn't Woody Allen marry his stepdaughter as well? Of course different countries = different laws. I do remember a lot of people making a fuss about it though, although the fuss they made was at least partially about cheating (I have no clue if any cheating happened, I wasn't there. They could definitely have made up that part).
This is oft-repeated untruth. Woody Allen and Mia Farrow were never married, never even lived together. Woody Allen married Mia Farrow's adopted daughter, Soon-yi. There was some cheating, though. Mia and Woody broke up when she found nude pictures Woody took of her (20-year old) daughter. Then Woody married Soon-yi, and they are still married.