Why does he expect for him to be level minded, after surviving a near death scenario and becoming berserk?
Is it that common to find oni children psychopaths/strong minded oni kids?
Common enough that it becomes the standard?
That also seems to duplicate whatever got resurrected. Also, that doesn't guarantee that the thing being brought back is actually the thing that was just dead, it might be another person altogether.
Glutton? Either her genes makes it so all her nutrients goes to her height, she's lying, she's sick, or just because of all the rules trying to halt kids growth.