It could also be that Humanity knows next to nothing about God's plan.  It could be that we are given exactly what we can accept while living in the physical and cultural reality we are born into.  I have no doubt if Genesis was written know, it would be vastly different in it's conceptualization of God and man's relationship to God.  Original sin would not be part of that mythos.  However, passing on the sins of the parents to the children would most certainly be part of the mythos.  We know from genetics, biology, sociology, and psychology that a child's view of reality and physical and psychological health are at the mercy of their parents...through their genes, economic status, birth culture, and propensity to engage in abusive behavior.  Unfortunately, much of this is generational which is why we need to do everything we can to break the cycles.