This is all excellent advice. Sounds like my hesitations were well-founded and the consensus is that it can do more damage than good at a young age, unless your child is exceptionally strong-willed and open-minded. I really appreciate the advice from those that have been there and done that. Leila Be, I think you are right in what you said about taking 30 odd years to reach a better understanding of things that you might not have at a much younger age. Like you, I think I would have had some major issues with my parents doing this when I was a kid. Like I said, even now, I might find this hard seeing it, but less so knowing it. The last thing I want to do is make trouble for my kids, and as we all know (and many have alluded to here), school can be hell.
I guess the thing that bothers me the most is the level of hypocrisy in encouraging honesty and being open about things in the family, but we can't discuss this...some things I suppose just do 'cross the line' and do more damage than good.
So, I will take onboard your advice. I know there is no hard and fast 'rule book' for how every family handles this, but I do know for a fact my wife is highly opposed to telling them for a long time, if ever, and I will be very wary of it myself, especially with my son. I really have no idea how I would address this until they are at least teenagers or living on their own and have some experience of sexuality under their belts. And on that note then, I probably don't have that much time left before I really need to guard my stash more carefully!