Simply put, behavior modification is when an authority figure rewards behavior they want to see, and punishes behavior they do not find acceptable. Behavior modification is often observed with children - grounding or time-out or loss of privileges if they do not behave as their parent expects. There is nothing wrong or inherently bad with behavior modification itself, when applied in a loving, consistent environment. Behavior modification becomes damaging when the authority figure targets the individual's self-worth and seeks to emotionally and psychologically injure the individual to get their way. The BITE (Behavior, Information, Thought, Emotional) Model was developed by Steve Hassan, an expert in cultic group behavior. Studies show that when one of these four categories is modified, the other three are soon to follow. This is due to cognitive dissonance - when there is conflict between these four areas, the person's mind seeks to make it all make sense again, and so adjusts the other areas not being modified to align with the one the authority figure has modified.
Your folks doesn't like or allow you to talk with "square" girlfriends. You are required to ask permission to take time off from work, to visit your family, to talk on the phone, or to leave the house (sometimes this comes to be viewed as being submissive and respecting his authority). You must ask for money to pay your bills or to go shopping. You are rewarded for making consistent quota or for knocking new wifeys. Anytime you are upset or happy, your first call is to him. Anytime something good happens, he claims it was because you obeyed him.