Dev had to remove incest/code option, you need a patch now. Get it here: https://lewdpatcher.com/game/my-new-family instructions are on this page as well.
I guess that was one on the older version of the game. I noticed it wasn't there anymore when I started up this edition after copying over my saves, and it doesn't carry the code over now, either. So that's unfortunate. I guess we now do have to download that patch the others had mentioned. Sorry for any potential confusion I may have cause for you!