What a wise reflection and a powerful concept of 'moral accounting' as something to not hold on to. The Tao of Pooh has left my hands seconds ago. The 1983 paperback first edition, with yellow pages than smell of sweet old paper. Thank you for reminding me of that gem.

The thing with loss and emotional maturing is that it is a long and painful process. To try to answer the question "Should a medical diagnosis reshape the past?":

Yes, for all the love you have. Let it. Even if it's false. Narratives that help you find peace and understanding are what you need. Think deeply on that the position of the father /might/ be right, but even false can be a wise position. It is so unlikely that a mother held her child and not loved the child fully and with the intention to raise it right. Circumstances (medical, life, ...) can get in the way. But hold on to that intention.