Most teens I meet these days lack basic social courtesy when dealing with people. My own son, who basically grew up with his grandmother, the original manners expert, has perfect table manners. This is partly because he was exposed to manners at a very young age. However, when we eat at home, he would not practice manners. So I asked him why. He said, "I behave the way I am supposed to behave when I'm out, but when I am at home I want to be comfortable." That's when I realized that most parents, myself included, do teach their children the proper way to behave outside the home, but they are also brought up to believe that at home, anything goes. My answer to him was "good behavior has nothing to do with where you are or whom you are with". Then he answered, "But I behave properly when I'm with others so that they think better of me ." And that is when I realized that I was doing things all wrong. I explained to him that it had nothing to do with what people think. This confused him even more. So I went on to explain that behavior, whether in your everyday interaction with people or at the dining table at home, is an expression of who you are. Well, at the age of 13, he got it. So basically, what I am saying is that teaching your children manners comes with the underlying lesson that it is not about what to do or not to do, but rather , who they are. This way it is not mechanical : it comes from within.  Teach your teens or children the basic courtesy of greeting their friends' parents and introducing themselves when they go to someone's home. Teach teenage boys to open the door of a car, or any door for that matter, for any girl, whether they are their girlfriends or not. This includes holding elevator doors or letting women step out of the elevator first. Just remember that teenage boys who practice good manners and courtesy grow up to become men who respect people in general. Why did "my son" behave differently at home and out of home?
He wanted to be a special boy. He wanted to be more comfortable at home. He just followed what his grandmother's said. He thought that behavior was very cool.