You are aware that Einstein's brain had some very unusual features, right? I don't pay much attention to this, but I remember it is unusual enough that it is safe to say most people's brains don't have those features.

Relativity was not a well-defined problem when Einstein came up with it. You can analyze this intelligence in however many ways, but it is highly possible that "quantum leaps" in scientific advancement come from unusual thinkers -- unusual in a way that you can't just train very hard in and attain.