I agree though that Lucas is full of it when he claims he had the whole saga mapped out. It's so obvious since there are way too many discrepancies. If he had originally intended to have Leia be Luke's sister, they wouldn't have Leia give him that big ole smooch on Hoth. If he had originally intended to have the words "midichlorians" and "padawan" in the films, then they would have been used right away. I think George had ideas of the way things might have been prior to and after Star Wars, but there's no way he had the whole darn story figured out. Had that been the case, the Emperor probably would have had a much bigger role in the OT, Padme would have either not died in childbirth or Leia wouldn't have remembered her mother. I'm guessing Vader wasn't originally intended to be Luke's father. That's fine and I think Obiwan's explaination in Jedi was good enough. It doesn't matter to me if George came up with the idea AFTER he made the first movie.
The fact that George makes so many contradictory statements and has created so many plotholes makes it obvious his original vision stuff is crap. How can an original vision change so much?