Using Social Media, AncestryDNA & Gedmatch to advance family research

Author’s Notes: All  All living males born with the last name Cumbo (or its derivatives) who have Y-DNA tested are invited to join our Cumbo US South Y-DNA project which can be found here –  https://www.familytreedna.com/groups/cumbo-us-south/about

Since writing this blog post, I have completed Y DNA testing of two direct paternal descendants of Britton Cumbo, and one direct paternal descendant of David Cumbo. The Britton Cumbo Y DNA descendants carry haplogroup E-M2 while David Cumbo Y DNA descendants carry haplogroup R-M269. This means, assuming no unexpected surprises in the direct paternal lineages of my testers, that David Cumbo and Britton Cumbo were not full brothers or even half-brothers through a common father.  Here’s the blog post on my findings.

I am a genealogy hobbyist who uses traditional research, genetic genealogy (the use of DNA testing) and social media to advance my research efforts virtually from my computer.

In last week’s blog post, How Hertford & Northampton Cumbos Connect?, I shared a theory that the parents of my 5^th great grandfather Britton Cumbo Sr. (b.1776-1794 and d.1837) of Northampton, NC were Matthew and Phoebe Cumbo of Hertford, NC, and that his brothers were David and Matthew Cumbo of Hertford, NC.

At the end of the blog, I highlighted the opportunity to validate this theory through DNA testing.  Well I might have moved one step closer to doing that thanks to social media and AncestryDNA.

Leveraging Social Media

I am active on Facebook and across a number of genealogy oriented Facebook pages where I share my blog posts.  I’ve found that sharing my research helps me to often connect with DNA matches, genealogy experts and other hobbyists, often fortuitously, who share my genealogical interests with whom I now regularly collaborate on research.

Last week I shared my blog post to the Hertford County Free People of Color and Their Descendants page administered by Dr. Warren Milteer. It generated a comment from someone who descends from David Cumbo of Hertford County NC.

Remember my theory is that my 5^th great grandfather Britton Cumbo Sr. and David Cumbo were brothers.  This person’s name looked familiar to me, so I checked my family’s AncestryDNA match list.  Sure enough it turned out that this person was a match to us.

AncestryDNA

One of the things I like about testing with AncestryDNA is that the service encourages users to link their DNA results to their online family trees.  This feature allows AncestryDNA testers to search their DNA match lists by surname and family location.  Additionally, AncestryDNA offers a feature that allows people to share their full DNA results – both ethnic admixture and searchable DNA match list – with other matches.

I messaged my match, for purposes of this blog let’s just call her Holly, and requested that she share her full AncestryDNA results with me.  Holly graciously obliged.  A quick search of her match list using the surname Cumbo resulted in 9 matches –  5 descended from Britton Cumbo Sr. and 4 descended from David Cumbo.

Match 1

Descends from David Cumbo’s daughter Susan Anne Cumbo of Hertford NC

Possible Relationship to Holly: 4^th-6^th cousin

Confidence: High

Match 2

Descends from David Cumbo’s daughter Susan Anne Cumbo of Hertford NC

Possible Relationship to Holly: 4^th-6^th cousin

Confidence: Good

Match 3

Descends from Britton Cumbo Sr’s son Britton Cumbo Jr. of Northampton NC

Possible Relationship to Holly: 4^th-6^th cousin

Confidence: Good

Match 4

Descends from Britton Cumbo Sr’s son Britton Cumbo Jr. of Northampton NC

Possible Relationship to Holly: 5^th -8th cousin

Confidence: Good

Match 5

Descends from Britton Cumbo Sr’s son Britton Cumbo Jr. of Northampton NC

Possible Relationship to Holly: 5^th -8th cousin

Confidence: Moderate

Match 6

Descends from David Cumbo’s son William Cumbo of Hertford NC

Possible Relationship to Holly: 5^th -8th cousin

Confidence: Moderate

Match 7

Descends from Britton Cumbo Sr’s son Britton Cumbo Jr. of Northampton NC

Possible Relationship to Holly: 5^th -8th cousin

Confidence: Moderate

Match 8

Descends from Britton Cumbo Sr’s son Britton Cumbo Jr. of Northampton NC

Possible Relationship to Holly: 5^th -8th cousin

Confidence: Moderate

Match 9

Descends from David Cumbo’s daughter Susan Anne Cumbo of Hertford NC

Possible Relationship to Holly: 5^th -8th cousin

Confidence: Moderate

I then invited Holly to the Cumbo Family Page which I co-administer on Facebook. This page has enabled me to connect Cumbo family members and share research with them.  Family members in turn have shared family photos and details which I’ve used to update my family tree.  The 2016 Cumbo Family Reunion in Williamsburg, VA largely grew from the virtual family connections created on this page.

Enter Gedmatch

It could be that Holly shares DNA matches with my family because we share the same single ancestor – Matthew Cumbo – the theorized father of Britton and David Cumbo.

But it could also be that we share different ancestors from the same area.  Pre-civil war free people of color communities often married within themselves, essentially cousins marrying and having children with other cousins – creating a genealogical effect known as endogeny.  In addition, there was cross pollination between Northampton and Hertford NC free people of color communities.  After all, it’s this assumed connection that underpins the theory that David and Britton were brothers.

To isolate the above shared match pattern to a single ancestor, I will need to determine if they share an identical DNA chromosome segment location.  If a mix of the above descendants of Britton and David Cumbo do share an identical segment location, it’s reasonable to assume that they inherited that identical segment from a single ancestor.  In the genetic genealogy community this is called genetic triangulation.

Notional example of identical shared segment match (green) across multiple DNA matches indicating they share the same ancestor from whom they inherited the segment.

To prove this out, I’ll need to convince my matches to upload their AncestryDNA raw DNA file to Gedmatch, a free DNA service for people who have already tested DNA with AncestryDNA, 23andMe or Family Tree DNA.  Gedmatch provides users the tools required to perform genetic triangulation.

The process to upload to Gedmatch is free, easy and allows DNA tester to maintain privacy. Here’s an Introduction to Gedmatch by Professional Genetic Genealogist Angie Bush