Tiger's Unfair Advantage
The average kid growing up in the U.S. doesn't get to play golf that often, unless they've got parents with moolah. Even then, it's a pretty costly hobby. (And getting more expensive all the time.)
Tiger's dad, Earl, though, was in the U.S. military. One thing about the military: they enjoy a lot of golf courses, and they get to play at a much lower rate than you and I. There may not be as many courses available now, with all the recent base closings, but for a while they had some premiere ones.
So, Tiger got to play...and play...and play. I'm sure he had the natural skills already, but it certainly didn't hurt to get a lot of time on the course.
Take a look at this article by David Holland to read about some of these military courses. One is listed in its top ten by Golf Digest, for heaven's sake.