yeah , this is an old argument . It is clear that George Lucas never originally planned for Luke and Leia to be siblings . Every piece of early Eu ran with the idea of a romantic connection between Luke and Leia . Splinter of the Minds Eye , which George consulted with Alan Dean foster on , and was intended to be a sequel movie if Star Wars was not as successful , ran with the idea . The Marvel comics of the OT era also did , even for a while after Empire came out . So , it is definitely there . There was no inbreeding because they were never originally intended to be siblings .In 1980 , my friends and I had conversations wondering who Luke would end up with . I thought it would have been Luke …wanted it to be . As an awkward kid , I related more to Luke and it was wish fulfillment for him to get the girl over the , bad boy ,jock ,cocky guy that Han was .If you watch the documentary From Star Wars To Jedi , Lucas talks about how he needed a reason for Luke to snap on Vader when hiding under the stairs and until that moment , he did not realize it was staring him in the face in form of Leia being his sister . So that was when that plot point came along .