Six Degrees of Separation on Capitol Hill

I know it's a terrible diagram, but I made it to show the point I am about to make. Our son and family lived on Capitol Hill for ten or more years. Our grandson was born here. We moved to DC to be in the neighborhood about ten years ago. Then our family moved to Virginia almost two years ago, but we stayed here. We recently went on a visit to visit the family in Virginia and brought my sister along. She said she was in an art class. She said her teacher was all excited about a house they bought. It happened to be on Capitol Hill. The art teacher described the house more. Then my sister's ears perked up. My sister said she knew that house and the people who lived in it. And wouldn't you know, her art teacher and husband bought the house that our son and family lived in. She and her husband had a baby boy like our son and his wife did twelve years ago. Of all the art classes and house in DC, there was a connection. Today, when we walked for our usual daily walk, we saw the art teacher leaving the house we used to frequent all the time. I stopped and asked her about knowing my sister. She said - is she in an art class? And so it goes. If you talk to someone long enough, something rings a bell.