Novel spoilers for the twins

Y'all I dropped this a while ago because my sister who read the novel said that Heinley isn't really a good father and ends up favoring his daughter way more over his son because she looks identical to Navier. The daughter knows this and has a very calculative and conniving personality exactly like Heinley's and ends up constantly bullying her brother (who was already very timid in nature) because she wants to be the heir to the throne. And literally barely anybody does anything to stop this??? I mean Navier does apparently try but it doesn't really do much...

This was vaguely what I remember her telling me. Do y'all think the author is gonna change this in the manwha adaptation? I really want to get back into this story but finding out that Heinley isn't as great of a father that I thought he was going to be absolutely broke me.

(Also I'm totally open for any fact checking since it's been a while since my sister told me about this)