I've read that that one of the worst things an author can do is think of their book as a baby because the emotional attachment will blind them to critiques. None the less, dropping my manuscript off at the post office to be mailed out was like leaving my baby on a doorstep. I did, after all, create and nurture the thing.
The experience got me thinking. Is it really so bad to think of your book as a baby as long as you realize that it's going to be criticized? Isn't that what happens to real children? They grow, go to school, are praised when they succeed and encouraged and instructed when they fail? Sometimes the criticisms are unjustified and sometimes they are. Parents talk to their children about the experiences and hope they learn from them.
Of course this is where the analogy ends because a parent cannot change the child not matter how much they may wish to. An author can make changes to their work if they agree with the editor or agent. Perhaps the books should be compared to cyborg babies; we create and love them, but know we may need to rebuild them. As long as the heart and soul is the same, what does it matter if some of the wiring and plating is altered?