What are the signs of abundant talent in chess?

I remember Fabiano Caruana as a little boy when he used to play at the Marshall Chess Club. It wasn't so much as the way he played, although it was impressive (and mature) for a boy so young, but it was the way he sat at the chessboard. During his games, his posture seemed perfect, his head hardly moved at all, and his eyes, almost without interruption, on the position he studied even as it changed as the game progressed. He projected a certain "quietness" if you will. This physical manifestation that Fabiano presented seemed to me to be a constant until each game was over. 

(BTW: I played two blitz games with Fabiano, one I lost and the other I was fortunate to win on time.)

I do not recall seeing this physical tableau to the extent that Fabiano exhibited in those days in any other child before or since. Of course my take may be influenced, subconsciously or otherwise, by how great he turned out to be.

When I taught in the New York City public schools, I noticed that the posture of certain extremely bright students was often different than the rest, erect and eyes focussed. 

I realize that posture and focus may or may not be a tell at all. And if it is, it may only be of value, along with the play itself and other factors ("signs"), when looking for indications of talent among youth.

This question, "What are the signs of abundant talent in chess?" I am intending not just for the young, but for players of any age.

Responses to the question are appreciated.

What's the matter, loser? Are you frustrated by your low ratings?

Some top chess players who do not wear glasses: Carlsen, Topalov, Grischuk, So, Mamedyarov, Svidler.