Leaders - are they born or are they made?

Are leaders born or are they made? According to Sir Rudy Giuliani, former mayor of New York City, they are made (after they are born, of course). Rudy Giuliani addressed a group of business professionals today at 'In The Room', a leadership and performance management event in Sydney. Whilst I may have a bias towards Giuliani (I'm a Yank, living in Oz, who happened to be living in the third largest City in the USA on September 11th 2001), there is no doubt he displayed amazing leadership during and after 9/11.