I'm referring to kids before even going to school. Ego / identity develops in kids by around age 5, that's when they see the I separate from the rest, they see the difference between what they have and what others have, they find this identity that only belongs to them in this sea of identities and they adjust and they react. I'm not sure if you've talked to kids before age 5, I've raised a few kids, and so I'm talking from experience.