If you ask her whether she is the literal daughter of Selune, she says Selune is her birth mother. I didn't get the impression she was unsure. However, Larian has many inconsistencies, to the point it's difficult to tell whether something is mistake, oversight, or a hint. Re: Astarion's tombstone. How old was he when he was turned?
Interesting, I only recall her going off about how she surely must have come from her celestial womb because she shines like the moon and so on and so forth, which is amusing either way because Devas ( not to mention Planetars and Solars even moreso ) would be endowed with similar, and greater, dazzling visages and abilities. So if she says that, either Aylin has gone insane after her century of torment/always been insane, which we do get some indication of in her interactions, and actually believes she's some 'special' daughter of a Greater Deity, or she's speaking metaphorically about being created by Selune. After all a Deity doesn't actually have to physically 'give birth' neither to their celestial servants nor to direct descendants imbued with their essence from a divine/mortal union, but it is pretty clear that Alyin doesn't come close to resembling a product of the latter. Even her personality and vocabulary just scream 'Deva', a perfect servant.
