I have more than one nephew, so I don't know which mindset is the right one.
Is it, "I know every fact about every sea creature and am not afraid to reel them off to my aunt at every opportunity"?
Or is it, "I'm too cool for all this but please let's dress up as knights and play with my castle"?
Or is it, "Mommy is the best, you shall have no other people besides mommy"?
Or is it, "I love my brother, but when he goes on about sea creatures too much, I will go off and secretly play with his things"?
Or is it, "Life is not worth living unless you can be moving around every second of the day"?
Or is it, ... Actually, I don't know. We haven't met yet.
Or is it, "I'm not sure if I'm going to be a boy or a girl, but it doesn't matter because I can spin around and sleep upside down."