Depends on the circumstances. If still a student, understandable. If down on luck for a short period, understandable. If employed and paying room and board, understandable. Otherwise, it may be time for you to find a place of your own. Your parents would like to have their lives back.
If it's OK for the parents, fine. Not My business. IMHO, the kid should be in university or helping with the bills and work somehow. If not working, can clean, paint, change oil, drive , help w/shopping, etc.