Random neural firing...
J. K. Rowling said that in her wildest fantasies of success, she never envisioned doing interviews where people were asking her what years Harry's grandparents went to Hogwarts.
Maybe it was Tolkien creating an entire world around characters that started it, or the cult following of Star Trek and Star Wars, but media used to be a lot less concerned with internal consistency. Larry, Moe and Curly were always the same people with the same personalities, but sometimes they were brothers, sometimes friends, or whatever. Their jobs and names changed to fit the plot.You just accepted that the Stooges lived in the 1800s, or were doctors, or private investigators, or whatever the plot demanded. Huey Dewey and Louie were Donald's nephews. There was no back story about how their parents died or ran off and they went to live with Donald. Their parents never existed. They were never written. Disney wanted young ducks to aggravate Donald, but didn't want a parent/child relationship.
The Luke/Leia kiss happened because in the first movie, they weren't brother and sister, yet.
The book (and movie) Coraline offers a pretty good example of the writing process. The "other mother" is the author. She creates a world based on the real world, but with variations. One of the characters has a lot of her traits. Some characters get out of hand, and seem to do what they want, regardless of what she has planned. Characters that cease to be useful dissolve. When Coraline tries to walk out of the world the other mother has created, the further away she gets from the house, the less detail. Finally, she's walking through nothing, because it doesn't exist. The other mother hasn't thought about it yet.
TL;DR: Conference realignment talk not going away.