Do you know this book?

My aunt is looking for the author and title of a science fiction book: “Do you know the name of a science fiction book in which experiments were carried out on babies, the babies had wings, the setting was deep in a forest, one of the babies escaped…..????”
I haven’t read it but my guess was either a Ray Bradbury type book or the female science fiction author that writes the language related books …
Do you know? (If you find it with Google or Amazon, I’d like to know which search words you used!)