It is very hard to decide when a story begins. The end is quite definite by comparison: A story ultimately ends when the protagonist dies, or, more cheerfully, when a certain era of their life has come to an end. The end is a bang is a shocker, the high point, the point of telling the story. The beginning is infinitely more subtle, more intangible. It has to go far back, enough to reveal all the decisions that were taken in order for the ending to occur. Yet the protagonist's birth cannot be credited as the beginning, since it is only an event in their parents' own lives. The parents' story would also have to be told in that case, and so on and forth. No, the beginning of a story is a completely abstract point, chosen simply because it immediately precedes a series of events, a chain reaction that will then lead to the ending.