The degree of freedom allowed will depend on SO many things....the perceived maturity of the kids, the interests they seem to have, the neighborhood and schools they are in, ....and the intangible 'general notions of propriety' held by the parents. (yes, they DO differ!)

and obviously, there is the practical problem of how to enforce what is 'allowed'. You can set a good example and try to hold their confidence, but you can't chain 'em to the bed!