Supposedly everyone on earth is connected to everyone else by an average of six steps of introduction, i.e., a friend of a friend of a friend, etc.  Last fall, Facebook and University of Milan scientists announced the average number of acquaintances separating two people in the world had dropped from 6.0 to 4.74. 

There is no genealogical theory regarding degrees of separation, but it occurs - eerily. During a recent segment of "Who Do You Think You Are?", actor Martin Sheen learned about his fourth great-grandfather, who was a prominent judge in Spain. Researchers found the judge had prosecuted a young woman for her scandalous behavior. A couple generations later, one of the young woman's descendants married one of the judge's descendants. They were Martin Sheen's ancestors.

When I started college, I became good friends with Marilyn, who lived next-door in the dorm. We grew up about 200 miles apart, she in Iowa and I in South Dakota. Nearly forty years later I had a surprise while researching my maternal grandmother's family. My grandmother, Hendricka Teeslink, wasn't born until 1883, but the 1880 census showed her parents living just a few farms away from Marilyn's great-grandparents - in tiny West Branch Township, Sioux County, Iowa - right there on the next page of the 1880 census. My great-grandparents moved to South Dakota in about 1886, but had my grandmother and Marilyn's grandfather played together as children?

Degrees of separation is another way of saying "It's a small world!" Did you hear there are two surviving grandchildren of President John Tyler (1790-1862)? This fact prompted another blogger to post a challenge of showing how far back in time you could go with two degrees of separation (i.e., you knew an ancestor who knew an ancestor). For example: If, as a baby, you were held by a great-grandparent (who was living and may have met his/her great-grandparent), you might be able to reach back to the 18th century. 

I found this was true for my half-Irish husband. His widowed paternal grandmother, Catherine Quinn Hickey (1873-1948), was a member of their household until her death; though he doesn't remember her, she certainly cared for him as a baby. When Catherine was a child in Dakota County, she lived near her maternal grandfather, Michael Rowan (1790-1883). So, in two steps, my husband could reach back to 1790. Check your own family tree and see how far back you get with two degrees of separation.

Speaking of separation degrees, what about cousins marrying each other? Charles Darwin and his wife were first cousins. In some cultures and jurisdictions, marriage between first cousins is prohibited. Interestingly, I've read that marriages between first and second cousins account for over 10% of marriages worldwide. While we might make "kissing cousin" jokes about West Virginia, everyone probably has thousands of (3rd, 4th, 5th, 6th, etc.) cousins if you research far enough. It's a fascinating subject. I wonder how many degrees of separation between the readers of this blog and me?