Fads or phases in music are funny things. I heard a new (to me) artist on the radio, Rachel Platten (the song was 1,000 Ships), and she reminded me of Regina Spektor (of Fidelity fame, among others). Which made me wonder if in fact there was a 'Regina Spektor school of music' that had been kicked off. Further research reminded me that Regina Spektor was, at least in some circles, seen as a progeny of Tori Amos - which seemed a bit of a stretch to me. But I do remember Amos seeming to kick off her own cycle of female musicians (and being seen as a descendent of Kate Bush, which also seemed a stretch to me at the time).
But it's also worth noting that right now the female vocalist is fairly popular - something to do with Glee and Adele, I think. It's all crazy complicated, but the idea that all of these pop phenomena feed each other and lead to each other is fun, if complicated to work through.