Difficult question! The answer is probably somewhere in between. You could argue that, coming from a comfortable, well off family who could afford a good education for him, was luck - but plenty of people come from a similar or richer background to Zuckerberg's and don't do anything exceptional.

As for his talent, he started working with computers very early. At 12 he created his first messaging program, Zucknet, which worked so well that his father used it at work (his father is a dentist). Again, he was no doubt lucky to have parents who encouraged him and friends who worked with him - he spent a lot of spare time making computer games with his school friends - but clearly the talent was there anyway.

While still in high school he developed software that attracted the attention of international companies such as AOL, and by the time he reached Harvard it was clear that his career would be exceptional.

So probably nobody succeeds without some luck, but it's equally true that Mark Zuckerberg has always shown unusual abilities.