Let's talk age restriction (& NSFW)

Sometimes a server wants to keep out the younger crowd, or due to some features or facets of their server, doing so is an imperative. They may be host to a particularly illicit mod or allow for ERP or what have you. How does an easy to use age restriction system sound, for servers? I figure the age could be fetched from profile data on the login server when a server checks. It's not perfect since people are liars on the internet, but it's something. Now, of course, an age restriction could be implemented through plugins and such... but no server would. Streamlining it such that it can be easily used and work silently in the background makes people much more inclined to do so.

Now concerning reasons why we might want to keep kids out of a server... What's your take on NSFW mods being developed for Mythruna? Without going into any specifics, is that something you'd want to restrict, or would you prefer to just keep it at arms length or let them go about their business? It's probably something of an inevitability if Mythruna gets large, so I want to see how you'll want to approach it.