I'm in a cliche in that my dad brought home a computer when I was young and I just started hacking on it. It was an Apple II and back then programming and using the computer weren't that different... it was so easy to start writing code that eventually you just started doing it if you used the computer for any length of time.
The thing that drove it home though was in high school I was super interested in how 3d games worked. I was in awe that computers were able to render games like Doom (the first version) with such a rich interactive experience. I really wanted to know how that worked so I bought a book called "Rendering Real-Time Graphics with DirectX" or something like that. That opened up the whole world to me and I loved programming.