That's kind of the consensus modern psychology and trainers are coming to. Some kids just have a drive that others don't, and that is what determines how well they do.

The major difficulty with the idea of "natural talent" is that every time someone points to a skill/whatever and says, "this is natural talent" someone else finds a way to teach that skill. Here is one paper: http://talentdevelop.com/articles/ITROM.html