Sorcha, It is true that you are more likely to find an aeolian minor scale rather than a harmonic minor scale in folk music, anything else you might say depends entirely on where the music you are listening to comes from. Eastern European folk music tends use a wide variety of minor scales, some derived from church modes and some from the older hexachords, and some from Turkish scales(which use a completely different system of intervals than we do)--and once you move into non-european folk musics, the rules of major and minor don't even come into play--even in the British Isles/North American traditions that we tend to talk about, there are a lot of variations on the scales, examples of which Bruce O has offered up, above--Even the minor melodies that we are familiar with have often been modified so that they can be played and arranged as more mainstream western music----