We have a fantasy world. A while back (like, 30-100 years; not really sure yet) a prophecy was given that basically outlined a chosen one. More specifically it outlines a reincarnate of a god who would do an important thing.
One of the characters in my story believes that he is the chosen one (he's wrong), and so do various groups and people around him (they are wrong). He later gets conclusive proof from another character that he is not the chosen one.
I have no idea how or why anyone else would begin to believe that he is the chosen one in the first place. Obviously, if the evidence for him being the chosen one is too strong, it will call into question the legitimacy of the debunking. Reincarnating gods are also not a particularly uncommon occurrence in this world, but not everyone believes that it actually happens, so any signals can't be so obvious that everyone in the kingdom would know the signs.
What are some common signs of chosen ones that could plausibly be found in someone other than the real chosen one?
If it helps at all, I don't really need to fool the reader, or at least not for long, since another character POV already knows he isn't really the chosen one. Also, it might not be hard to get him on board initially, since he quite likes the idea of being the chosen one.