(That being said, passion / perseverance / intelligence can often lead to focus)
Arent those more of a prerequisites for focus? Focus is merely a side effect not something you can aim for.
In the case of our painter, if we're talking about Michaelangelo or something, he'd likely come out with an excellent IQ.
As an aside, IQ tests don't try to make you do math problems and the like, it's all pattern matching kinds of questions where you learn all of the necessary context in the test itself. Which makes sense right, it's trying to measure your ability to learn and generalize, not what you happen to know before you take the test.
One I recall vividly was basically a page full of weird symbols and a "key" at the top mapping symbols to numbers. I had to go through the whole page converting the entire page and various elements of my performance (variance of speed, attention, etc.) were measured during the task. This does not really correlate to what I'd consider focus or "flow" during typical programming tasks, however, but it did try my patience! :-)