Yes, pretty much all my family know and as far as I'm aware pretty much all of them are atheists as well, or perhaps would identify as such if they considered it. It's not such a big deal over here; we even got rid of our ridiculous blasphemy laws years ago (so I love it when someone accuses me of blaspemy - it's one 'crime' I can't be guilty of!). Out of all the members of my family, I'd say my Dad is the one who most closely shares my views, on this and many other issues. His interest in the subject has certainly increased this past year or so and he often picks my brains about it.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'