The KDrama started with beautiful caring simple yet beautiful and pure concept of a family where kids not related by blood started living emotionally and share there relationship as pure brother and sister till their teens and schooling. This a clearly evidently mentioned many times in starting 6-7 episodes that they share brother and sister emotions and relation. The story was adorable.

But the story started becoming uncomfortable to watch with family when a brother falls in love with his sister and started looking his sister as lover. May be in many countries, regions and cultures this relation is seen as forbidden.

A family exist when their is emotional attachment and caring among the relations, it doesn't matter whether they are blood related or not. How could a brother emotion changes to lovers emotion for his sister? Isn't it a taboo relation? Its a disturbing relationship. Majority will agree it will impact the mindset of brothers and sisters in a family watching this KDrama. The story becomes even sickening when the sister says her brother that she looks him as oppa (big brother) and still weird minded oppa trying to persuade his sister to change the relationship from siblings to lovers by starting it over again.

I don't understand how actors (Hwang In-youp and Jung Chae-Yeon) accepted such forbidden relation concepts? Are they so desperate to make money and agreed to do the Kdrama?

If the story demanded the romantic relation the director of the KDrama should have taken care of the script and should not have mentioned the relation as brother and sister between the two characters right from the beginning, then this would have been one of the all time great KDrama.