- those who, like this article describes, had hacked since a young age (sorry for the gross generalization, but these tended to be middle or upper middle class white males)
- those who had maybe taken AP Computer Science in high school but otherwise had no real programming experience (these tended to be minorities in race, social class, and gender)
i remember that despite the best efforts of the teaching staff to 'level the playing field', the people in the former group clearly had a much easier time while many people in the latter group were intimidated by those in the former group (even when no ill will was intended). i dunno where i'm going with this anecdote, but that just popped into my head :)