I grew up with all three original Star Wars movies already made. Luke and Leia being siblings is something Ive taken for granted since I first watched the movie, when I was too young to remember. But the fact is, theres nothing to suggest theyre siblings in the first 2 films. Nothing at all. In fact, theres a lot to suggest theyre emphatically not siblings. The brother loophole was a way for Lucas to write himself out of the love triangle between Han, Luke, and Leia. It didnt make sense as part of the plot, and it wasnt consistent with the characters up until that point. It was just stupid. It was how he avoided dealing with the plot hed created.