Your mom might just be looking out for you. To be honest, some parents think restrictions (here on music) can avoid getting their children into trouble. My parents have never really cared about what I listen to. Nowadays I'm listening to jazz and classical, most of the time - I also like some songs from other genres. I've been down the dance- (~2005-~2009), and the heavy metal path (~2009-~ January 2010). I recall listening to "Disturbed" (I believe they're called), but, today, I can't really understand why I was listening to metal.
What I'm saying is, she probably just want you to avoid getting into trouble... I believe.