The past will always be buried in one's mind, no matter how old they grow. Even if you tuck it away behind a doorway, it will knock from time to time to be let out for you to explore it.
Yet it is never childish to hold onto one's past. Quite the opposite. For you realize what you have come from and accept whatever you are now.
For all its ups and downs. Your past is an aspect, but it is no longer you.
You're better now.