ask them if they want to change the world. i knew i wanted to try and do something 'big' when i was a kid (not that i had any idea what that was ;-). i went into the physical sciences not programming but even at that age i would have heard if someone had said 'software is changing the world - you can be part of something amazing'. that, combined with access to other people, would have been enough for me to plug into a hacking culture. as it is, i was pretty lonely until i got into post-grad and found other people out there with the same attitudes.