does television create fads or does television follow fads already occurring?

there is no mistake that when there is a huge new fad (mostly among young people) television is right there along with it.

examples: emo, grunge (flannels and what not), big hair in the 80′s.

also it is a lot of times associated with a new music.

does tv create new fads or does television follow new fads already occurring?

and if tv creates new fads why does it seem a lot people are so willing to follow it?