I heard Ginny say in an interview that Mary Margaret was “forever 28.” So as far as the cast knows, she and Emma are the same age. But the creators are funny about that kind of stuff, so they could always change it at some point. I honestly think it would be hilarious if she were younger. It would make for a fantastic “WTF” Emma face. 😆
No one has ever mentioned how old Charming is though. I kind of think he may be younger than them,
I think it’s probably a plot hole about Regina and Maleficent’s conversation, keeping in mind that was, what, the 2nd episode? Everything about Snow’s age is pretty confusing to me though, because when she’s first banished it’s clear she isn’t supposed to be much more than a teenager (which Ginny acts wonderfully) but by the time she meets Charming she’s hardened, used to the wilderness, and seems much more mature, leading me think years could have passed since her encounter with the huntsman. And after he breaks her sleeping spell, they had an ENTIRE WAR to fight to reclaim the kingdom. That had to have taken a while. The creators say they have everything mapped out, but as awesome as they are, at this point I think they’re kind of making it up as they go along!
But then, it’s FTL…so I guess we should take all timelines with a grain of salt.