Is this music okay for my little sister to listen to?

My little sister is 13 years old. She loves to listen to all kinds of music, like 80's, 90's, heck, even the 50's. Her favorite 60's song is The Alvin Show (Alvin and the chipmunks). She thinks now and days music is just stupid and idiotic. Is this okay, or is my sister just a weirdo. Please answer.