We built nderground for people over 18. With this caveat, I’ll note that a private social network like nderground (http://www.nderground.net) allows you to connect with your close friends and others that you explicitly choose. This means that you avoid the unintentional exposure of social networks like Facebook.
It takes a bit of work to build your network of friends (we call it a Karass), but the reward is that a lot of the toxicity of public social networks is avoided. Our hope is that nderground is a venue where you can be yourself.