You know, as someone who loves folk music, folk stories, folk art, etc., I'm not too sure of the mechanisms behind how something goes from "someone's song" to a "folk song" or "someone's story" to "folk story." I've heard it argued though, that a hundred years from now, people might know the tunes and lyrics to artists like The Beatles or Bob Marley, but not necessarily know who originally wrote and performed them, effectively making them folk songs. But then, we would still know who made them, so they also wouldn't be folk songs. I dunno. Everyone seems to run by different definitions and maybe that's part of the problem.
I've also heard it argued, somewhat convincingly actually, that kids in their bedrooms recording themselves playing the guitar and covering other artist's songs, is basically the 21st expression of folk music. It's just that the community has gone from a public gathering to the internet.
At least your wife isn't singing Lady Antebellum or Florida Georgia Line or something.