I just saw some pictures of Iraqi kids playing in a war ravaged town and swimming in a makeshift pond in the middle of the street. It dawned on me that most kids left to their own devices will have fun and make their own happiness regardless of how wealthy their family is, where they live, and what shape their country is in.

I think it's more about how you are socialized and who you live around rather than any external material factors. Basically the people you grow up with and around determine a happy childhood.

I also think some kids are more predisposed to happiness than other kids just like adults are but much of that is learned.