Tell the tale from the beginning...?

"The tale the beggar tells must be told from the beginning," wrote Elie Wiesel. Indeed. I understand the point made by the statement, even though I'm reading it in a vacuum, devoid of any context. It speaks clearly to me, and in volumes. Obviously a beggar's story can't be complete without including the path that led him to begging. But what strikes a chord for me, regarding this quote, is the question it seems to inevitably lead to, once you've arrived to the aforementioned conclusions. Must not everybody's tale be told from the beginning, if there is to be a full faceted understanding of his/her story?
I'm not going to attempt an essay on the subject, though I probably should. The truth is I'm too lazy to try. No, I just want to use this statement to add to my understanding of my novel's central character. He is the sum of many parts. To wit, his genes, upbringing, education and life experiences are the most fundamental of those parts which have contributed in some way to carving his character and personality. But these are painted on with a very broad brush. There is much minutiae within each contributor that shifts the balance of influence one way or the other. My dilemma is whether to consider these only for the sake of character development, or use them as a part of the narrative (be it in the form of biographical details, flashbacks, or as retrospective explanations for decisions made throughout the story). Perhaps it's best only to consider them privately as the writer, and allow them to shape the character in my mind before committing it to paper. Hmm...