As far as I know only one of my friends is on GN - and she is a friend made through GN. Obviously I would not publish anything about her, but I do refer to my family, but nothing that would embarrass them if they did see it, other times I will not write on certain subjects because I do not think I have a right to because the experience is owned by another member of the family. With friends I will fudge the story. make a few changes to ensure they are not recogniseable.
But at the end of the day very few family problems or events are unique to one family, Lots of people share the same experiences. The family of my DGS's best friend is exactly the same as DGS's family, children, gender and order, the fathers both do the same unusual job but not together. There are a whole lot of fairly unusual characteristics they share. If I wrote of them in a recognisable way. It would still not be clear which family I was talking about and for all I know other families in the same city might match the family profile.