Here's an interesting article reported by the TImes Online in March this year. It's a geneticist who's essentially saying that being a 'genius' is simply a matter of practice. Download from here.
I recently read another book which stated something very similar about extraordinary people such as Bill Gates, the Beatles. The book is called Outliers by Malcolm Gladwell. The book goes through case studies where he appears to show that being a 'genius' in these realms seems to require an accumulated 10,000 hours of practice on the area in which you are a 'genius'. That is a lot of hours and it's only possible if the environment is conducive if you want to be a Girl- or Boy-Wonder.