"Should I tell him that I'm not his biological father?"

Hello Mr. Hutten, I have a question for you. I have a 14 year old step son who does not know that I am not his biological father. His mother and I have been separated for 9 years. I get him and his brother, who is my biological son, three times a week. I have had this visitation arrangement with their mother for the entire 9 years. I met the boy when he was 8 months old, and he really has no idea I am not his biological father. That said, the boy treats me with no respect, gets into trouble and generally makes the time I have with him and his brother a nightmare. I could go on, but I am sure you can imagine what I have been going through. My question-- Should I tell him that I am not his biological father? I really want to tell him because I do not think he appreciates exactly how good I have been to him. I spend a lot of time being angry at him and I think if he knew the real situation he might have a little more gratitude. Please let me know what your prof...