I guess it depends. If they're a legal adult and still living in their parent's house, they need to abide by the rules the parents establish even if it sounds ridiculous to not be allowed to drink or have to be in at a certain time. Other than that and if the adult is living on they're own, the parents should have no say over what they do. I do a few adults who still abide by their parents orders as to what type of car to drive, where to live, when to start a family, etc. I think it's ridiculous and the adult "child" should "cut the apron strings" and move on with life.