Music and Our Generation's Taste

The other day while I was driving back from dinner with my girlfriend and her family, a song came on the radio, it was "Only the Lonely" by Roy Orbison. Her parents were surprised that both my girlfriend and I actually liked this sort of music, the very smooth and rockabilly-esque nature of Orbison's hits. This made me wonder why music has shifted so much throughout the years, and why it has ended up where it is now. A guess I would have would probably be how the industry itself has shifted. Has it merely been the popular vote of the generations? As we know, history constantly changes, and the tastes of the people constantly change as well. This is how Elvis music can be timeless, but certain other artists like Huey Lewis & The News may have fallen out of fashion with some of the younger crowds. My question to everyone is, do you think the change of music throughout the years is mostly because of individual people's tastes, or is it rather an industry capitalizing on whatever sound they can get a hold of to earn more revenue?