How? They are step-brothers, right?
Plus, Royals do incest. Cleopatra was married to her brother.
It still wrong even if their step brothers, adopted ETC. And Royal do marry within the family but it's usually 3rd cousins and forward. Unless you mean Old Royals, they usually did marry family members brothers and sons/daughters... ETC For example: Oedipus
Also,this is a manga so even if we read incest is not like were thinking of doing the same think. (I hope) I like reading incest stuff related or not related but in real life i hate it. lol So think of it as a guilty pleasure :3
Yeap incest and shota are like my guilty pleasure I read a lot of them in yaoi but in real life I can't stomach them. I read a novel about incest and I almost burned the book.
CRYING I know it's wrong but I'm rooting for them