I have always, always, ALWAYS written. Seriously, as cliche as it is for me to say that, it's true. That's the one thing I've always been praised for by my teachers: my writing skills.
Of course, I do think this came about because I consumed about 6 books a week regularly from when I was five to when I was thirteen. Yeah, I was pretty much a bookworm. I read during recess. Now that I've gotten older (ha ha, 16), I find I spend most of my time writing rather than reading, and since I read much more complex and longer books, I don't have the time to go through half a dozen in a week. I'm lucky now if I get through one every two weeks. I know, shame on me.
Gosh, I'm ranting now. No, the books that made me want to be a writer are probably the Harry Potter series. I started reading it when I was in fourth grade and I just couldn't believe how many people were reading them, especially the kids in my class that I knew didn't read. From that point on, I knew I wanted to make that kind of an impact on kids. And the rest is history!