"Train up a child in the way he should go and when he is old he will not depart from it." That's Proverbs 22:6 (KJV). But many have misunderstood this verse to be some kind of a "character guarantee", one that absolutely demands a certain outcome if the first conditions are met. But there is no such promise inherent in this verse. By exegetical definition, a proverb is a general truth, a wise evaluation of how life usually works. But not always. Free will is a fact of life -- for those raised right and those raised wrong.
A better understanding of the principle of Proverbs 22:6 would encourage parents to go all out in providing love, biblical instruction, and examples of holy living to their children. But it would not interpret the verse as a mathematical certainty. And thus it would remove a great deal of anguish, confusion and blame (blame directed at God Himself, among others) that so often results when a child does "depart" from the ethics and values established by godly parents.
Dennis Prager has a handle on this principle and he writes with great compassion about the suicide of James Dungy in this Town Hall column. In doing so, Mr. Prager can help ease the false guilt of many other parents. It is a very good piece.