Surviving Genes of Walling and Dey

I have figured out the most recent common ancestors of a DNA cousin.

A new Shared Ancestor Hint appeared for me at AncestryDNA.  This system compares the family trees of my DNA cousins, looking for the same ancestors from my family tree.

The shared ancestor suggestion was William Walling (1770-1824) of Monmouth County, New Jersey.  He is one of my 5X great grandfathers.  (His transcribed will can be found here.)  I don't know why his wife, Rebecca Dey (born about 1770), my 5X great grandmother, did not appear also.

Based on our family trees, this DNA cousin is a fifth cousin of my father.  AncestryDNA reports that I share some DNA with this fifth cousin.

Here is the step where a lot of people stumble:  this scenario does not prove that William Walling and Rebecca Dey are our biological ancestors; nor does it prove that the DNA we share is from William Walling and Rebecca Dey.

We need to see how much DNA and which segments of DNA are shared with this DNA cousin so that we can triangulate the match.  You cannot triangulate with AncestryDNA.

To triangulate, we need to look at other DNA cousins who match on these same shared segments of DNA and determine if they too trace ancestry back to William Walling and Rebecca Dey, or one of the ancestors of either of William Walling or Rebecca Dey.  With AncestryDNA, you have no information about where any of your other DNA cousins match you, so you cannot know if they match on the same segments as any other DNA cousins.

I remembered the name of this DNA cousin from 23andMe, where we had corresponded two years earlier.  We had discussed the idea that the common ancestors were not too far back in time and were likely in Monmouth County, New Jersey because this DNA cousin matched my father, his siblings, and their father's cousin from the Winterton/Dunn line in Monmouth County.  If this segment can be further identified as a Walling/Dey segment, then we know that the segment came to my father via William Winterton's mother, Sophia Walling.

We can see the shared DNA at 23andMe.

Note that one of the matches, a sibling of my father, shares a very tiny segment of only 5 cM.  Most people would disregard such a small amount, but as you can see in the graph, this small segment is in line with the larger segments shared by other close relations.

Prior exchanges with this DNA cousin at 23andMe did not lead to William Walling and Rebecca Dey because his family tree had not yet grown that many generations back.  Two years later, his family tree at Ancestry was more robust and prompted the discovery.

The next step is to look at the other DNA cousins who share this segment.  I maintain Excel spreadsheets for my closest relatives.

This snippet is from the spreadsheet of my first cousin, twice removed.  I list his DNA cousins by chromosome of where they share identical DNA.  The Walling/Dey cousin shares an identical segment on chromosome 7, starting around 91,000,000 and ending around 127,000,000.

I checked all of these smaller matches against the Walling/Dey cousin to see if they match him as well as my first cousin.  All of them do.  If this shared DNA is from the Walling/Dey couple, then all of these DNA cousins will also descend from Walling/Dey or from one of the ancestors of either William Walling or Rebecca Dey.

This is where you need to depend on others for information.  Some of these DNA cousins offer family tree information; most do not.  I reviewed their surname and location lists and family trees, if they had any, and saw nothing in common with Walling/Dey.  I sent them all a note, describing what we need to look for.

So far, nobody has replied.  Without finding a connection to Walling/Dey in these other matches, we cannot triangulate to declare that this segment of DNA is from Walling/Dey.