Almost no Degrees of Separation

This is a photo of a portrait of my grandmother-in-law, which was on the front of an invitation to an exhibition I went to 23 years ago. Although I come from a long line of non-entities, my partner, B's, grandfather was a reasonably well-known artist in his day and he painted this portrait of his wife. 

One convivial evening, around the same time as the exhibition, a friend from two streets away noticed a drawing on our mantelpiece and said to his artist wife, 'Hey, that's by your great uncle'. We were puzzled - it was by B's grandfather. We looked at family trees that didn't quite join up in the middle but we didn't pursue it and just told all our children that they had some new-found cousins in their primary school.

Perhaps everyone has cousins in their primary school but is just missing the drawings on the mantelpiece through which to make the link. Or perhaps it was really weird. 

Roll on two decades or so to this afternoon, when I was sitting in the office needing to check something on Facebook. I hate Facebook. I don't understand how things can be there then not be there and I use it as little as possible. Reluctantly I dug out my log-in details. And there on the screen was an arcane conversation going on between my brother-in-law and my nephew-in-law about a painting connected to the drawing on our mantelpiece. Why they were doing it on Facebook and not by email I have no idea. I clicked on 'View more replies' and was astounded to see a post from someone called Finola, a name I know from freespiral's journal, alerting none other than freespiral to the conversation, despite neither of them being FB friends of mine.

OK, so B's grandfather was Irish, but Facebook has 2.5 million users in Ireland. What are the chances?