A Matter of No Consequence Whatsoever

I have fairly long hair in a classically plain mousy-brown color. You know, the kind that girls in books always complain about (excepting Anne Shirley). It's thick and coarse, there's a lot of it, and it has juuuust enough body to be unruly.

There are, however, a few exceptions.

A few strands here and there are nappy. I can't think of how else to put it. This ain't curls, yo.

And this isn't because I pulled it and split it, either. You can tell when that happens, because the frizzy bit is all at one end, and the rest is straight - it's like curling balloon ribbon.

My hair has been this way as far back as I can remember. Every now and then I'll notice one of these. Anyone have any ideas??