I like it when taboo themes are handled like this, present in horror/psychological stories and are used to portray the dark side of humanity. The incest is a fundamental element of the story, without it, the whole plot doesn't make sense and the events wouldn't occur in the first place. (Kinda spoilers) Jin and Lee grow up twisted because of the toxic environment they were in. And them having a happy ending doesn't mean author is romanticizing incest, we just see them being happy despite the dark circumstances that led the type of love they felt for each other get distorted.
I like it when taboo themes are handled like this, present in horror/psychological stories and are used to portray the dark side of humanity. The incest is a fundamental element of the story, without it, the whole plot doesn't make sense and the events wouldn't occur in the first place. (Kinda spoilers) Jin and Lee grow up twisted because of the toxic environment they were in. And them having a happy ending doesn't mean author is romanticizing incest, we just see them being happy despite the dark circumstances that led the type of love they felt for each other get distorted.