On the accuracy of Ancestry.com DNA predictions

I'm very impressed with the DNA test administered by Ancestry.com. They report that I have over 600 fourth cousins or closer but I have confirmed some even more distant relationships. See below for the most distant relationship that the DNA tests reveal.

In the vast majority of cases the people who share DNA markers with me have no family tree that's on Ancestry.com so it's impossible to say for sure whether we are related. There are often clues based on who else shares our haplotypes but unless the person reveals their name and some of their ancestors that's all I can do. I usually contact those people who could hep me sort out some unknown relationships but I rarely get a reply.

The ones who already have a tree are much easier because then I have a list of names I can search and, furthermore, they are much more likely to correspond. We've found some of our common ancestors by comparing notes but in many cases we can't make the connection because one of us is missing some key links. The most interesting discovery was a 3rd cousin relationship from someone whose parent had been adopted but who didn't know their biological parents.

Some people have detailed family trees so it's possible to trace the exact connection and the results confirm the DNA prediction. There are no false positives so far but that's not surprising since it would be very difficult to prove that two putative DNA matches are NOT related. Each of the subjects would have to have a very detailed and accurate family tree extending back more than 7 generations and it would have to include all ancestors plus all siblings and their descendants.

The most distant connection so far is a seventh cousin once removed. We are direct descendants of two people who lived more than three hundred years ago! Daniel Robbins/Robinson (1627-1714) was born in Blair Atholl, Perthshire, Scotland. He was a Scottish soldier fighting on the side of King Charles I in the English Civil War when he was captured and sent to the colonies (Connecticut) as an indentured servant. There he met and married Hope Potter (1641-1687) and they moved to Woodbridge, New Jersey when he had served his time.

A seventh cousin and I share a French Canadian and a Dutch ancestor from the former colony in New York—Peter Montras (1715-1790) and Emmetje Anderzon (1717-1790). Peter was born in Phillipsburgh (Tarrytown), New York and he was baptized in the Dutch Reform church in Sleepy Hollow [Sleepy Hollow]. His parents are buried in the sleepy hollow cemetery (see photo). Emmetje Anderzon was born in New York (formerly New Amsterdam).

There are lots of fifth cousins. Here's an example of a connection to the Fraser clan in Scotland. John Fraser (1754-1807) was born in Inverness, Scotland just eight years after the Battle of Culloden. His wife Isabella Mackay (1762-1856) was also born in Inverness. They emigrated to Canada in 1803 with their five children.

So far I've established 25 direct connections to my DNA relatives and there are another 25 or so where we know our common ancestor but not the details. There are three problem groups in my tree but, unfortunately, the DNA results haven't helped sort them out (yet).

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