I tell people I started writing when I was 12. This is pretty much true. But I was always making up stories in my head, usually involving what I built out of Legos.
My sister, who is four years older than I, brought home her touch type instruction book from high school. I used it, and her typewriter, to teach myself how to type. I then started writing. But what influenced me to become a writer?
1) Television: As a kid I watched way too much television. But, in a way, that's where I learned to tell a story.
2) Star Trek (the original series): When my local television station started running Star Trek reruns in the afternoon just after I got home from High School, I watched religiously. There were two episodes they didn't show, however, "What are Little Girls Made Of?" and the last episode, "Turnabout Intruder." I had to see those later. (I think the television in my small, very conservative area of Idaho found them unacceptable.) But Star Trek is what made me a science fiction writer.
3) Books: What writer wasn't influence by the books he read. And I read, of course, science fiction books.
4) Robert Heinlein: Speaking of books. In an about four-year period from 1986 to 1990, I read every Robert Heinlein book in print. And I love most of them (he had a couple of early clunkers like his first juvenile with Nazis on the Moon). But man, could he write. And I wanted to write like him.
5) Star Wars: In the sixties and seventies, science fiction tended to be boring and depressing or both. Then the original Star Wars movie came along (and its two sequels) and I realized science fiction could be fun.
Those five things are the primary influences that made me a writer. Well, that and I've always told stories.
What influenced you to do what you do? If you write, what influenced that? Let me know in the comments below.