I'm not exactly sure what "folk music" is, although I think I've been playing at least some of it for the last forty-five years or so. Claiming to be a "folk musician" is sort of like claiming to be a "science fiction" writer (and I do a little of that, too): I figure the best bet is to do the best you can and do whatever you can to avoid genre labels. If people like it, nobody will care what it's called. And since one of the members of the group I play with has 20 years of classical piano training and 30 years as a piano teacher behind her, we do a fast, finger-picked guitar and hammered dulcimer version of "Fur Elise" (words available upon request) that I call "Fer Elise" except when we start it with the first eight measures of Beethoven's 5th and call it "A Fifth fer Elsie". It cracks up the piano teachers and students in the audience, and probably counts as some sort of "folk music", I suppose. Just do your best and have fun!