Quote Originally Posted by Enkidoh View Post
Basically, much of 1.0's early storyline was actually bouncing in and out of the Echo, specifically others' memories of the year 1562 6AE when the Archons (namely, Yda, Papalymo, Thancred and Y'shtola) first arrived in Eorzea under directions from Louisoix. Back in 1.0, the Echo was rendered differently to how it is here in ARR - in 1.0 it was virtually indistinguishable from reality (you can still see this if you view the 1.0 opening cinema movie which is found easily enough on Youtube), and the only way you initially could tell the difference was an Echo scene begun with a subtle woosh effect and a soft gong sound. Other than that, you had absolutely no idea before Minfillia taught you how to harness the Echo at will, when it would literally ask you to use it and so there was no confusion.

Also Thancred was definetely an adult (or at least in his late teens) when he first arrived in Ul'dah - I still have screenshots of the scene in question of my old 1.0 alt that started in Ul'dah and he was clearly physically (and acted like) an adult:



I'm not sure about Thancred's exact age though as it was more Gridania's 1.0 story I was taking notice of, so Professor Moose or one of the other 1.0 loremasters would be better to answer this question as they're much more knowledgable on the subject than me.
Other Weirdness: Quest Text from 2.1 Build on The Stone.
Minfilia: Let us set aside the matter of this Ascian until after we have completed our move to the Rising Stones. There is but one final favor I would ask of you before I depart.
Minfilia: I believe I mentioned before that my father was a member of the Ala Mhigan Resistance. The truth, however, is more complicated than that.
Minfilia: As far as the Empire knew, he was their spy. He maintained the deception for nigh on half a decade, furnishing the Resistance with vital imperial secrets while feeding his paymasters subtly conceived misinformation.
Minfilia: When he died some fifteen years ago, my father left behind his journal, which I have closely guarded ever since. It contains every shred of information he and his agents could steal on what they believed to be the single greatest threat to Eorzea: the primals.
Minfilia: Its wisdom has guided me through the years, though there is much within I still do not understand...
Minfilia: It is my hope that Urianger will fare better.
Minfilia: Tell him to treat it with care. It is all I have left of my father.
(Optional)
Minfilia: Please, before I reconsider, give my father's journal to Urianger.

Now Who's Right?
Either The Twins are now 21 as of Shadowbringers because F'lhaminn remarks at Quest Text: One Final Journey Warburton died 20 years ago.