Ciaran, I think I've got it!
The song I have is off a tape called One Size Feets All with Anne Dodson and a few others. Pixie Lauer sings a Rosalie Sorrels song with this chorus: But we're not one we're worlds apart you and I, child of my body, bone of my bone, apple of my eye.
Is that it? It's a lullaby written for a teenager.