Reality is not perceived the same way just similarly experiences help shape and define each persons view of reality. That how we have likes and dislikes . You are trying to oversimplify perception and reality in correlation to the brain and how it develops over time with experience.
I perceive myself much the same as anyone else. Learning to accept that I am not truly a singular entity is a continuous process
that's an illusion. every familiy is more unique. if they weren't, every child would understand the same things in school, find the same things easy and difficult, and that just ain't so. and its not even so of children of any one ethnicity either.
I would say that the childs understanding is based off of several factors. First is the acceptance of the singular being, this is done by observing the reactions of those around the child and then simply asking why. In other words this singular identity is formed because it makes the most of the accepted reality we find ourselves in. The second is the acceptance of our parents perspectives on this reality. The third is acceptance of manmade law at its base form. As such we are taught to believe in the self and we grow this belief through living it. I believe unity to be inherent to all things. It is the acceptance of diversity that makes unity seem hard, necessary, and acceptable.