What is genius

 
This is not expert opinion, just me thinking out loud.

It is impossible to see everything that is happening around you at once. It is also impossible to interpret all of the signals that we receive in sensory input, like what we are seeing, hearing, smelling... Examples of abilities associated with interpreting signals are that some people are able to read others responses like a book, others can play chess really well, still more can apply their huge database of knowledge to the appropriate situation at any given time.
For an extreme example of this, think of the movie Rain man. Dustin Hoffman's character was not able to interpret the social situations that they encountered, yet he was a "genius" at numbers. But not at every aspect of numbers, at memorizing numbers, and at doing arithmetic with them. Point covered, on to the idea.
What is this "genius" ability? I think there are many different abilities, and some of them combined together form a strategy for comprehending the world. Lets make some assertions, then see which prove out.

-one person can not have every ability.

-If your ability is to focus in on one ability, you lose out on the opportunity to have it's opposite.
(If you don't agree with me yet, see where we go, hold on for a little and try me)

-These abilities combine to form a strategy unique to that individual, but through different strategies can come to similar results, with differing successes in speed, and accuracy.

and the last assertion (no drum roll please)
-Being a really realy good genius ( not evil or anything) comes from having the ability to instantly and continually decide if the ability you are using or focusing on is the one needed for the situation.

I will edit this to actually talk about it when I am not so tired.