I am an only child. When I got my first teaching job in my early 20's, I still lived at home. My parents did figure out "rent" for me to pay. They also bought me a car and I made "car payments". Found out later that all of the money I had paid them was put into a savings account and given to me when I got married. It was enough to help with the downpayment on our house and to pay cash for a new car.
I'm not short...I'm fun size!