Quote Originally Posted by Tlamila View Post
I'm not exactly making it up, it came up quite often in discussions about it.
But if you want a source, looking it up very quickly this is from official race description: "with lifespans one- or two-tenths again as long as their fellow races, their physical maturity is somewhat delayed. It is not uncommon for Wildwood children to look up to their Hyuran friends in their early teens, only to rapidly outstrip them around the age of twenty. "
This is for Wildwood but should apply to all Elezen, if you want more sources I'm sure you can find them, i just did a quick google.
That's exactly what I said?
(Emphasis mine)

They age 1/10th to 1/5th slower.
That quote was pulled from the Encyclopaedia Eorzea, which I literally pulled out to check before making my post.
At the most generous (1/5th slower) this means that when a Hyur is 50, a Elezen born the same day will effectively be 40.
Someone aging 1/5th slower than another will make next to no difference at Alisae and Alphinaud's age.