Well, my parents met when they were 17 years old. They didn't really date seriously at the time, and they certainly didn't talk marriage then. But they did eventually marry, and some twenty years later, they are still together.
Of course, they had just recently come in from Vietnam, so their environment was very different. Maybe living in Vietnam just forces you to grow up fast in order to earn money and take care of all your younger siblings.
I'm 18, but I don't think I'm controlled by my hormones now. I certainly was back when I was 14, but at this point...well, you all know what my feelings on girls are. Good looks are nice, but great conversation is better. And if she has any interest in fiction writing...
And I know my roommate is capable of real love. He was 19 up until recently.
Then again, my roommate and I are definitely on the older side of the teenage spectrum.