I write the stories I write because they are the stories I want to read. Fandom has a huge appetite for stories that are nearly identical - first times, aliens made them do it, h/c, etc. - and I think that's as much on the writing end as on the reading end. I do know that my stories tend to be repetitive - I like to examine the same themes from minutely different angles, and I'll keep doing so until something else interests me. I wouldn't recommend reading them all in a row.
Food for thought. I know fandom loves the same stories over and over and over again (when I was active in DCU writing, "Kon helps Tim relax" stories arguably made up about half the fandom), but I'm not sure if I could say that about myself or not. It's been pointed out to me that I've written about parents and children a number of times, but I don't know if there's any real thematic component to that. That said, Robert Heinlein said (in "On the Writing of Speculative Fiction," OF WORLDS BEYOND, Fantasy Press, 1947) that there are only three stories: boy-meets-girl, The Little Tailor (i.e., a character's rise or fall, or both; think SCARFACE and MILK for a couple of disparate examples in film) and the-man-who-learned-better. The specifics vary from story to story and from fandom to fandom, but in general I would say that the story I write over and over and over is "the-man-who-learned-better." My stories tend to be about characters learning things: about themselves, about the world, about what to do or be, with the result that they wind up in a different place then they started out in.
I don't repeat specifics much; at least, I try not to. I think that my tendency to not write romantic pairings probably helps, but I think I'd feel kind of awkward doing boy-meets-girl or boy-meets-boy if I kept writing first times about the same pairing. It brings to mind Tom Lehrer's patter about folk songs: "finding singing fifty verses of 'On Top of Old Smokey' twice as enjoyable as singing twenty-five," and whatnot. :)
I dunno. How would you guys peg me? And how would you peg yourselves? Make it a meme if you want; I think this is a neat question, and I'd like to see more people answer it.