Ive been told Im considered an adult child too after doing a test during a group. Basically its when you go from being a child who has to act like an adult in a sense, because you are exposed to or forced into situations that a child shouldnt deal with, ie pushed into working/competing, abuse/neglect where you end up needing to look after yourself or someone else in a way a child shouldnt have to, anything that causes you to have to 'grow up'. Then as you get olds you end up going from a child who is an adult to an adult who is a child, in a sense. You dont have that transition from being a child to becoming an adult, so some of those 'childish' traits may stick around in you personality, like depending on others, and not being as good at coping with things emotionally. I dont know if that all made much sense, but I hope it helps a little.