Precisely. Current societal views and social mores apply here, not those from the Bible nor any other work of fiction. (See what I did there?) Going down that rabbit hole, Adam and Eve obviously had kids, right? In order for there to be more children, eventually there had to be some dad/daughter, mother/son, and/or brother/sister copulatin' going on, else the entirety of the human race would have stopped in its second generation. If that's our example to follow, we basically have carte blanche to fuck whomever we'd like without fear of reprisal since we're all inbred anyway. I guaran-goddamn-tee that modern society doesn't function that way, so why bother referencing it, y'know?
Now, if you'll all excuse me, I'm gonna go be thankful for evolution. Because thanks to it, I've never inadvertently fucked a member of my family. Which is pretty important.