Does virtual pedophilia lead to real-world crimes?

Here's (yet) a(nother) thing I have never thought about.

In Second Life - the venerable online role-playing game that goes back to the early days of the internet, but which apparently is still going - you can inhabit a virtual avatar, and carry out virtually most of the things you do in real life, including having sex. Because individuals in the game can choose the age, gender and appearance of their virtual characters, that means that it is possible for a virtual adult character to have sex with a virtual child.

Now, pedophilia is illegal and ethically verboten in the real world. So, should we be concerned about people doing it without repercussions in the virtual world of Second Life? Some people definitely are concerned, and some Second Life players and others have vowed to expose such activity within the game. There is also pressure on Linden Labs, the manufacturers of the Second Life software, to actively disallow such behaviour.

But it's not a slam-dunk ethically. How is it any different from a person just imagining the activity in their head (which, so far at least, is not illegal)? No real-world children are affected by it, so is it not just a harmless (if slightly weird) pastime? Might it even prevent potential pedophiles from committing real world crimes, in the same way as child sex dolls do for some people? And what about all those violent computer games that involve torture, killing, even mass genocide - shouldn't they be disallowed as well (many would say to that, "Hell, yeah!")?

It seems to me that our attitude towards such games should be informed by the extent to which they might encourage such illegal activity in the real world. For example, there is plenty of evidence that violent video games desensitize players and may well encourage real-life violence (the teenage Columbine murderers and the Norwegian mass murderer Anders Breivik being oft-quoted cases in point). There seems to be less evidence that virtual underage sex leads to real-world pedophilia, but the picture is far from clear, and it could quite conceivably be a valid issue.

Tricky one.