What Trish said... you can't parent him. Someone else did that already. They may not have done the job you would approve of, and when that is the case, then you have to think about what you want in your life. This is who he is. Do you want that in your life? Can you live with it, without blaming him and nagging to change constantly? If the answer is yes, then its yes, stop punishing him for something you are willing to accept. If the answer is no, then move on. You can't parent him, but you can decide on the course of your relationship with him.