Is the virtual world a significant part of our modern lives? Absolutely.
Children and teenagers go there and spend a significant amount of time there? Who would argue?
Do parents worry about what their children do online, what they'll find there, and who they'll meet? Of course they do, and who wouldn't?
Journey into the brave new world of virtuality with them, and not only will you have nothing to fear (every world carries both danger and beauty), but you'll be able to place as many milestones along the way as you want and can.