I mean, I've just told you I have the book, but I can also repost the relevant pages so you can read them for yourself and see that there is no birth year set in stone for Cullen in it:
So you can see, no specific date. You can calculate a date backwards based on him being around 18 to 20 by the time he was assigned to Kinloch, but there is no hard date. Whoever wrote the very specific date of 9:11 at the wiki was just calculating backwards based on the assumption that he was exactly 18 when he went to Kinloch. They didn't pull it out of thin air, but it's not official lore either.
eta: removed the last part because R2 was more to the point, so. Yes. What she said.
And as I said, I wondered how someone was getting that specific of a number without pulling it out of their tuchas. A valid point, And R2 to the rescue.
Wasn't trying to poke you, riverbanks, but it seemed damned weird that it wasn't like Hawke's estimated age since unlike some wiki I've seen DA community tends to be pretty damn good about being accurate, so I trust the information.
But even with it being +/- a year, my original point remains about Hawke being older and thus amusing as hell.
As for the whole life experience thing, I base a lot of my assertions on research done for a different project. Nothing DA related, but I find it a decent real world analog for templars. Very specifically a book called 'What Cops Know' by Connie Fletcher. It's an oral history of police officers who served in Chicago's Detective Area Six in the 70s and 80s.
To make a long story less long, the cliche about police getting a somewhat... jaded view of the world and their fellow man isn't. Some of the stuff here is nightmare fodder. And while it isn't one to one, when Cullen talks about lyrium's effect on the memory, and that the older templars tend to welcome that forgetfulness because of things like past falled Harrowings. I can't imagine developing emotional scar tissue fast or go nuts.
Cullen doesn't seem to have that in the mage origin. He's got a rather romantic view of what he's doing, which is why what happens next hits like it does. And while this next bit is pure headcanon, I have no trouble believing that of all the surviving templars in the tower, Uldred torture Cullen for that exact reason. Well that and there are mountains that will move sooner than Cullen when he puts his mind to it.
Speaking of canon, where do those pre da 2 shorts fit?