I have a confession to make... Unfortunately, your opponent will not be your childhood but instead it's official representative: your infancy -- which has been hunting your childhood's bones all along. And, according to sources speaking on terms of anonymity*, "it's so sweet, it's like taking candy from a baby."
But it won't be your infancy that you fight either, actually; from within your infancy's blood appears your pregnancy term -- and from within your pregnancy term appears your conception.
You will fight all of them as one opponent.
* you, much later