All of them? I was a voracious reader. How could I pick just one? Maybe Little Women or Island of the Blue Dolphins was instrumental in shaping me. But it could have just as easily have been The Lorax or Are You There God, It's Me Margaret. How long does childhood last? Into Junior High/Middle School? Then maybe it was Mark Twain's Huck Finn or all the Heinlein books I read. I give up. The question is just too hard.