What About The Title - "Original Sin"?

What is the significance of the title?  What were your thoughts as you first began the book and then after you were well into the book??  Title means so much and is the heart of the book, and in a series they can be as integral to the mystery as the plot, setting and characters.  What does the term "original sin" mean to you??  Is it just a biblical reference or does it go even deeper?  Have fun thinking about this topic and let us know your thoughts.