How do you view the best way to go about regulating the age of people visiting your site? Do you see there being anyway to deter people who are, for example, under 18, if your site only is meant to allow people over 18 to visit it.

There's a lot of talk at the moment about regulating the internet, especially regarding pornography and minors, but is there really a way that it can be regulated without infringing on the rights of interest users / website owners?