Ah, but the mother's dna has been passed on to the daughter's dna, and subsequently to the grandchild. That's why this was posed as an exception to your absolutist statement, and certainly, since there are no absolutes, there can be other exceptions. Such as a sibling acting as a surrogate, even a cousin. And in some cases even when an egg or sperm are donated from a 3rd party relative, known or unknown.
During the early 60's, scifi author Ted Sturgeon posed a world where all births were surrogate, all sperm and all eggs from the same two King and Queen donors. A world of clones envisioned before genetic science theorems had reached heights of today's cloning possibilities. A method of obtaining peace, because cloned siblings would not kill each other. Until the purpose of war in his story, by an unidentified enemy, genocidal deaths of the king and queen, ending the future of the human race. The vulnerability of his suggested exclusive surrogate pro-genesis. Another negative outcome of the Frankenstein monster, man playing god, Mary Shelley's accusation of men abandoning the women they impregnated, their offspring to the unknown petulance of life.
This thread isn't about a woman's right to do what she wishes with her body, nor is it about exploitation. Mere subterfuges for fear of men playing at being gods, and the inevitable retribution of jealous gods. Fear is the true name of this game. Fear of science and the powers it gives mankind, the powers of jealous gods. Fear of men being replaced by test tubes.
:rofl