Let me give you this perspective. I did not know more than my parents, even when I though I did. I was mad at the way they had the double standards. my brother could do anything he wanted and i could not, just because he was a boy and I was a girl. But even with all of that, I was tought to respect my elders and my house, I would never raise my voice or challenge my parents, (it wa better to just do it behind their back). Now that i have kids (2 teenagers 18 and 13) i have given them a little more freedom than what I had, but they know how much they can push. My 18 years old started College this Fall and I told her that all I asked was for her to finish school before she decide it to have kids and be crazy in life not to do something she might regret later, like gasp, getting pregnant at 18 to live her life the fullest with reponsability and good health, she tought I was the craziest mom out there, but then she came to me a few weeks ago and said, "I see why you gave me that advice my friend had to quit College because she got pregnant, her parents kicked her out and now has to work to pay her bills.
Teenagers may think that they know more than us, but we did too, but at the end of the day it all has to do with how we raise them that matters.