"What's past is prologue"

I've been hearing a lot about finding your "core" story, or the theme of your life that you habitually write into your stories over and over again. I've finally figured mine out. If I look back on the four books I've written (well, I'm currently finishing up the fourth--only about 20 pages left to go!)[*Author's Note: It's finished! Critiqued! Spellchecked! Revised!], I realize the theme of each is that those events that occur in our past shape our future. Or, as Shakespeare said, "What's past is prologue." My characters are often people who have had some life changing event, often a tragedy, occur in their youth or formative years. This event changes them forever, sometimes casting them adrift until they learn to search for and find the meaning in their lives. The characters would have been completely different people if it hadn't been for that event, and in the end, it makes them stronger once they learn to overcome it.

This realization hit me out of nowhere, and I must admit it has been the theme of my own life. What's past is prologue, and I tend to think that is true of most people. What was the event of your past that shapes your writing today? Think about it.