@salinas Adding to your comment because I'm that annoying 🤪
In a purely biological perspective, there's some theories about an instinctive aversion, fuelled by evolution, towards inbreeding (genetic variability is a very important determinant for the resistance of a species, after all); but incestuous relationships were relatively common until the 17th century, specially between nobility and royalty. There's also arguments about the taboo not having biological motivations, since society clearly displays discomfort towards affinity siblings relationships. It's not really about justifying incest, but rather rationalize something that it's part of human interpersonal relationships, y'know.
South Korea, historically, has always been strictly against consanguineous marriages. People with same surnames couldn't even get hitched, blood related or not. So it's needless to say that it's a very sensitive topic to throw around. That's probably why the author decided to make Hari an adopted kid.
Anyway, people have all the right to be bothered but it's also really simple to just... Stop reading. With the incest tag or not, it's kinda obvious since the beginning that something like this would develop. The manhwa's name is Beware of the Brothers. There's romance and drama tags. I mean-