um ok that explains why suddenly I could not reply to something...
that said the point is that were talking about what goes on in a games Story. a lot of games that actually have a story in there somewhere have some fairly hard restrictions in place that break the story if you try to change them,
Luke and Leia were siblings, and not lovers.
Spock is the child of a Human-Vulcan relationship
Laura Croft is the tomb raider.
Kazooie is a Red bird with a yellow beak who rides around in a bears backpack.
The Warrior was a tribal.
The Lone Survivor is the Married parent of a spouse and child who he lost in part because he decided to trust Vault Tech because of the chance that something would go wrong. you can make whatever you want of that backstory. (perhaps the spouse is a good friend and one of you wanted a child who would not be a "bastard" and then WWIII happend