User blog comment:Master Sima Yi/Assassinews 05-08-'14 – Assassin's Creed: Rogue announced/@comment-4892808-20141026210025

So, I got the idea Arno is not born with eagle vision, but has to learn how to use it, the same way as gavin does. The previous protagonists had developed their eagle vision really early on, not having to activate it for a limited amount of time. Edward says he always had it, Giovanni knew about ezio's ability, and Connor uses it perfectly as a child.