User blog comment:Master Sima Yi/Assassinews 03-12-'14 — New Assassin's Creed in Victorian London leaked/@comment-173.189.47.87-20141228220746/@comment-13471981-20150105075416

Yeah, as Fairy said, Eagle Vision has been retconned and technically any human has the potential to unlock it. There's a few like Desmond and the player characters who are able to access it quite naturally, but they are no longer the only ones that can have it.

The coresponding symbols is more of a coincidence than anything - Unity just plastered those on a wall and didn't do anything with them afterwards.

By the way, Abstergo got the dna material from one of Arno's descendants, a guy called Robert Fraser.