Adolescence is not a contagious disease
If we treated any other group in society the way we treat teenagers it would be an ism. Imagine if we spoke about old people the way we speak about teenagers. Imagine if we treated people of a different race the way we treat teenagers?
We regard being a teenager as an illness they will recover from, and a contagious one at that, one that is best avoided. Men who are further down the line on fathering will tell me knowingly how one day my little darlings are going to turn into monsters and want nothing to do with me. The general gist is that they are best left alone for 10 years or so and then they will come back.
I have to admit that teenager is a term of abuse in my house. There are certain ways the elder one has of reacting that are a bit 'Kevin the teenager' and I'll say, "Oh, you're a teenager now, are you?" And she will take it as the worst possible insult. When she sees real-life teenagers I notice her observing them very closely. They are exotic to her, and she is fascinated by them, but she knows that they are bad. She will watch a group of shady-looking young ones for a while, and then she'll lean into me conspiratorially. "Dad. Are they teenagers?"