There is another part to the why I write question--what book made you a writer. Many people read a book and it inspired them to write. They thought "I could do this" or "I want to do this." It's a common question--what book inspired you to write.
There are a great many books which have influenced me, but none of them caused me to pick up a pencil while I was still a child. That honor goes to my mother. Her favorite way of punishing me was to send me to my room, sometimes for hours. That didn't bother me. I could still do my favorite thing, read. She could put my body wherever she wanted. My heart, mind and soul lived in Narnia and Oz. She decided it wasn't a real punishment if I could still enjoy myself, so she took all the books out of my room.
She couldn't stop my very active imagination. I would sit by my window and imagine a prince coming to rescue me from the witch who stole me from my parents. Many imaginary friends kept me company and we came up with stories together. Eventually, I started writing down my stories as a form of rebellion. I told my mother I was doing school work.