Parents define a person. Yes genetically-of-course, but equally by being their primary and formative influences in almost everything. And obviously, functional parenting quality ranges from great to traumatic to non-existent.

Therefore there is no greater variable in nominal differences between youth peers. How could there possibly be?? It is near all-encompassing, and sustains for the first quarter of a persons life.

This concept is true going back through the ages, with the main difference being less social and economic mobility in the past. That does not = 100% social or economic mobility now, by any means.