How Much hair does a normal Head of a young person have?

On random occasions, Letting kids chose their own hair style is a step in letting them become independent though it is a little one. I let my kids start choosing their hair style when they started taking care of it them selves. Keeping it washed and combed. This was way back in the 70s at about 10 or eleven My son of 17 wanted long hair which was the style. He had to keep it off his neck and neat. The girls had to keep it clean and out of their eyes. My youngest daughter wanted long hair.