Exactly. That was my point. If I read the threads on FB I don't bother seeing who has commented on there- there are irrelevant when most of those on the thread don't know they are reading it!
I only commented to make the point that it is all connected- beyond FB- onto Pinterest, Google, TripAdvisor Twitter and others. Therefore it is useless saying that you are not on something like FB when lots of your opinions are on there for all to see.
To answer OP it is not surprising . Don't link accounts, watch your privacy levels, be careful how you sign into sights and don't have a profile on GN. (Unless of course you are quite happy with it all.)