Maybe "opinionated" cleaves closer to the original question. There's probably a medical term for the trait, too, when it is expressed pathologically.
As for teenagers, I think they are more attuned to and less tolerant of differences in opinion than adults. I think this sensitivity to opinion is one of the major forces that drives them (usually non-traumatically) from clique to clique. Who likes a new band? "They're my new friends, and everyone else is stupid." That is, until the next great thing comes along next week. Hypersensitivity to opinion is the opposite of not acknowledging the opinions of others.
Acknowledging the value of the opinions of others is a different story, and here I agree that some people are either raised to do so, teach themselves to do so, or are genetically predisposed to do so.
