We think we are anonymous, but anyone who really wants to know about us can use the (admittedly awful) Gransnet search box to find our past comments and add up all the things we have posted - location, type of house, what is in our front garden, number and age of children, job, spouse's job, colour of grandchildren's school uniform, view from windows, whether we are on Facebook, why we chose our username (so many people say "because it is a combination of my name and the cat's" or some such thing)
Several years ago, I noticed that one Gransnet poster (who is no longer a member) had posted that she was on facebook, with some other personal details. I was aware of security issues, so I decided to see whether it really was possible to find someone. I found several people on Facebook who could have been her, but then she posted something else which was confirmed by one of those Facebook accounts. On that Facebook page were photos of her, her house, her children and grandchildren, a list of where she had gone to school and worked and a whole lot more.
I did absolutely nothing with the information, and I can't even remember any of it now, but it showed that total anonymity is very difficult to attain.