AC97
("[Timestamped it":](https://youtu.be/Xl2Ub7LmVlE?t=92) for "not exclusive to alicorns;" Twilight would've furthermore immediately called shenanigans on the basis of "hey, you're obviously not an _*alicorn,_* so you doing that should be _*impossible_*, so what's going on" if that were the intended implication.)
Furthermore, if you're taking a note or two from Journal of the Two Sisters (which has a few aspects reflected in show canon, like what happens to regular unicorns when they raise the sun, losing their magic and all), Celestia and Luna are naturally long-lived, due to being natural born alicorns (which the S6 premiere"[seemed to heavily imply the _*opposite_ status*,":](https://youtu.be/CxY13jU2rIE?t=33) them possibly ascending [and there'd be no discernable reason for them not to chime in with "we were born that way too, but to both alicorn parents, if we recall correctly"), and Horse Play only said that Celestia was Star Swirl's student, not alicorn status or the lack thereof, and then there's how the Tree of Harmony's origin got retconned as well, in S7), and Star Swirl had used an age spell on himself, specifically, that he'd created.
Furthermore, if you're taking a note or two from Journal of the Two Sisters (which has a few aspects reflected in show canon, like what happens to regular unicorns when they raise the sun, losing their magic and all), Celestia and Luna are naturally long-lived, due to being natural born alicorns (which the S6 premiere