One thing to consider about cultural phenomenon like rock'n'roll and hippies is that they rise out of cultural mixing. Rock'n'roll for instance grew out of rythm'n'blues and country, or rather out of black culture in america mixing with white poor culture. From there you can go on to say that it grows as a way of young people looking for a way to be in opposition to the the established structures, but it doesn't originate in that drive.
Hippies also didn't appear because of the Vietnam war, they arose from beatnik culture and a new western fascination with eastern spiritualism.
Similar things can also be said about older cultures, where it seems again that interesting things happen when people meet.
Consider for example what happens when early Christians travel to Greece and Rome to spread their faith and mix with the cultures they meet. Christianity goes from being a small, eccentric mystery cult to a sophisticated and state sanctioned religion in a relatively short time.
Another thing to consider is how cities and states grow in relation to trade routes. For example, the biggest cities in the UK were the port cities. This is also where cultures mix and interesting things happen.
Another earlier example is how presocratic philosophy has been theorised to have grown out of culture melding in the Mediterranean area.
It is when we meet other people that do things differently than ourselves that we gain the ability to question how things have been done in the past. This is important to consider when it comes to youthful rebellion and cultural differences between the classes, if the difference is more than how much they drink and how foul the language is, then the inspiration had to have come from somewhere.
And also furthermore people who adopt traits and aspects of somebody else's culture stands a lot freer to change it through their interpretation and desires than the original holders of the culture. Take the high heeled shoe for instance. It originates from Persian riding boots used by men and was imported to Europe as a masculine fashion, worn even by kings. But in Europe it was first and foremost a fashion and as such it wasn't bound in interpretation by traditional use. The shoe was kept, the idea behind if mostly forgotten.
Similar things can happen with musical traditions or ceremonies when they are taken up by new people.