I was talking to Rhian about this today--how the hell did we end up being writers? Our parents, though quite literate, are not very literary--my folks are not big fiction readers, and Rhian's read mostly nonfiction, or genre fiction. My running joke about my childhood was that my mother was always telling my brother to come inside and read, and telling me to put down that book and get some exercise.
In my case, I think it's a combination of my father's love of the amusing anecdote, and my mother's obsessive need to set things straight. Because of Dad I appreciate a good story; because of Mom I'm able to actually finish writing one. Rhian claims she gets her love of character from her mother, a British expat who is always analyzing the way people are different from one another (Britain vs. America was a big topic in Rhian's house, back in the day); I would imagine her gregarious psychologist father has something to with it as well.
The first writing experience I remember is typing a poem on a big manual that sat in our basement, on top of a salvaged school desk, the kind with the inkwell on the corner. I've got that poem somewhere among my papers (I once planned to write a "review" of my juvenilia and extracted all the old stuff from my mother, but never got around to doing it...too self-indulgent, I guess, even for me), but I remember the last line: "Upon his tombstone yonder."
I've actually published several things--a novel and a short story that I can think of--which actually contain a tombstone yonder. Some things never change. I never have gotten around to writing any science fiction, though--the genre that made me love reading. I will, though, someday yonder.