You really dont get the story do you ..??? I taught the same but I re-read the story again. Basically in the beginning she was able to maintain her adult like appearance because she was a baby and no one can judge her, but as she grew she had to learn how to act her age in order to be loved by everyone and that includes her father (which I think myself is very adult.like) but as time flew by she even felt childish and didnt know the reason why it was happening . Which in my opinion is something of a natural for it to happen after all her mind may be of an adult but her hormones and body is still of a child so you cant really blame her if her body appears her mind. ALSO her dad and her maids act more like children then herself
I fucking hate her she is an adult from the future for fuck sake she should act like it instead of being a royal brat he could be your child you now