I'm out to my family, my friends and anyone else who may ask. I don't advertise usually, but am an open book to pretty much anyone who asks what I believe or how I live.
I do have three kids, and I haven't volunteered any information to them. Once they reach the age when they start wondering I'm sure there will be questions....and at that point they will get the full poop as well.
This goes for pretty much everything in my life, though. Not just Poly.