If you're of an adult age and still living with your parents - you're not grown.
I walked in on a thirty year old cousin arguing with her mother because she was not afforded the freedoms generally associated with someone her age.
"I'm grown", was the response of the daughter.
"Oh hell no. You're not 'grown' until you are responsible for yourself.", I said.
"You're only 'grown' when it's your house. Until then, you're only a guest.", I finished.
As the daughter slammed the door and left the house for the home of her boyfriend - the mother reminded me that her mother lived with her.
"Yep,", I said, "your mother lives - with - you. You're 'grown'.".