Honestly guys, if you're just going to yap about that here, and say you don't like the story at all, just don't read it. Drop it. Ignore it. Erase it from your history or something. You guys are ruining it for people who do like the story, people who don't really see the main characters as real "siblings". If you have a problem with that, then, as I said before, JUST DROP THE MANWHA. If you knew at the start you don't like it from the moment Cesar said shit about Adelaide, then just drop it all together. You're just torturing yourself, and others too.
It'll be better for both sides, you guys won't stress out about the "borderline incest" you see, and they won't be bothered as well.