Reading Behold A Pale Horse again.
If you've never read it or even heard about it, I highly recommend it.
And for the parents of ABW or those who plan on having kids, I'd recommend reading The Nurture Assumption: Why Children Turn Out The Way They Do by Judith Rich Harris. It gives a well supported alternative theory as to why children end up being so different despite grow in up in similar circunastance. Basically states that parents in our society have less influence on a child's personality and they turn out then commonly assumed. And that their peer groups and friends in school have a major influence impact on them from a very early age. Very insightful.