Is this rock n roll?

We listen to a wide variety of music in our house, although most of it is "Pop" music.  If you ask Merrick what his favorite song is, he'll tell you "Hey Soul Sister" by Train.  On our way to Y camp this morning, Merrick and I were listening to Nirvana's "Smells Like Teen Spirit" and he asked me "Is this Rock n Roll"?  I told him, it's considered Alternative music and I asked him if he liked it.  He said "YES!" Since I was a teenager in the 90's, Nirvana and Alternative music holds a special place in my heart and hearing that my child likes it, makes me smile.