Tuesday, October 22, 2013

An X-chromosome Match Provides Needed Clues

Two weeks ago, a new relative, Ernest Johnson, appeared in my and my mother’s 23andMe relative database. This one raised eyebrows because he shared significant DNA with both of us. With me, he shares 0.52% (39 cM) across 3 segments.  He shares 0.68% (51 cM) of DNA across 3 segments with my mother and is a predicted 3rd cousin. In my opinion, that’s closely related, considering that 98.6% of the 635 people in my mother’s relative database to date are predicted fourth, fifth, and more distant cousins.  Also, I noticed that he looked familiar to me, so I decided to see if he had a Facebook page. He had one, and my mouth dropped when I discovered that I had met him before!  Ernest is a member of the Atlanta chapter of AAHGS (Afro-American Historical & Genealogical Society). We had met at several AAHGS meetings. He also attended a Black History Month presentation I had given in Atlanta. Amazingly, a lot of people, who communicate with each other, are clueless that they are related and not-so-distantly related in many instances. We truly live in a small world.


X-chromosome Matches

The “treat” about our not-so-distant connection is that 1 of the 3 segments (21 cM) falls on our X-chromosomes. That definitely means that the connection is on Ernest’s mother side, since males inherit their X-chromosome from their mothers.  X-DNA matches are great because the X-chromosome can only be passed down certain ancestral lines.  Therefore, ancestral lines where the connection would not be found can be eliminated.  I can immediately eliminate Ernest’s father’s family, Ernest’s mother’s paternal grandfather’s family, and my mother’s paternal grandfather’s family.  I utilized the X-chromosome Inheritance charts located here to eliminate those ancestral lineages. 

To add, females inherit two X-chromosomes, one from each parent. Their paternal X-chromosome all came from their father’s mother (i.e. paternal grandmother).  In other words, as the chart shows, a female inherits exactly 50% of her X-DNA from her paternal grandmother.  The remaining 50% consists of varying amounts of X-DNA that were contributed by her maternal grandmother and her maternal grandfather.

The Ancestral Possibilities

Fortunately, Ernest has been researching his family history since 1977; he has identified 7 of his 8 maternal great-great-grandparents, as well as several 3X-great grandparents. Since 23andMe predicted that he and my mother fell within a small range of 3rd to 4th cousins, this indicated that the chances that they are indeed 3rd cousins or 3rd cousins-once removed were good.  Third cousins share the same great-great-grandparent(s). Ernest and I both had researched our families a great deal; therefore, figuring out our fairly close connection shouldn’t be that difficult. Right? Besides, a predicted 3rd cousin, Delia, appeared in my father’s relative database. After she shared some information with me, I was quickly able to determine that she and my father are indeed 3rd cousins-once removed. Delia’s mother and my father share the same great-great-grandparents. Delia and my father share 0.53% (39 cM) of DNA across 3 segments, a little bit less than what Ernest and my mother share with each other.

Ernest conveyed that most of his 8 maternal great-great-grandparents were from the same general area, Caswell County, North Carolina and bordering Pittsylvania County, Virginia, between Danville, VA and Yanceyville, NC.  Because we’re an X-DNA match, I can eliminate 3 out of the 8 using the male chart.  Hence, our connection is through one of the following 5 people:

(1) John Holderness, born c. 1837, Pittsylvania County (Danville), Virginia
(2) Elzy Roan, born c. 1848, Caswell County (Dan River district), North Carolina
(3) Mariah Johnston, born c. 1833, Caswell County (Dan River district), North Carolina
(4) Henry “Harry” Hatchett, born c.1826, Caswell County (Dan River district), North Carolina
(5) Jane Hatchett, born c. 1830, Caswell County (Dan River district), North Carolina

Ernest was even able to identify the parents of Elzy Roan and Mariah Johnston. Additionally, an elderly couple, Sam (born c. 1780 in VA) and Nannie Hatchett (born c. 1805 in VA), who lived adjacent to Henry & Jane Hatchett in 1870, may have been one of their parents.  Interestingly, the white Holderness, Roan, Johnston, and Hatchett families were slave-owners in Caswell County.

For my mother, X-DNA matching eliminates her paternal grandfather’s family (Barr / Reed), which had a Virginia tie, and her maternal grandfather’s father’s family (Davis). Genealogy research eliminates a majority of my mother’s enslaved maternal ancestors, who were born and enslaved in various counties in South Carolina before they were taken to northern Mississippi. They and their ancestors had been in South Carolina as far back as 1800 and likely even further back into the late 1700s. Time frames and locality eliminates the rest of my mother’s maternal ancestors.  These eliminations left the two strongest possibilities – one of the parents of my mother’s paternal grandmother, Sarah Partee Reed (1852-1923). 

The only known North Carolina link in my mother’s family tree is indeed through her paternal grandmother. Fifty percent (50%) of my mother’s X-DNA came from her. Grandma Sarah’s mother – my mother’s great-grandmother – was Polly Partee, who was born somewhere in North Carolina around 1830. Somehow and someway, she was taken to Mississippi and became enslaved on Squire Boone Partee’s plantation in Panola County (Como) by 1851.  Sarah’s father may have been a man named James Partee, who was born somewhere in Virginia around 1825. Was Polly Partee or Grandma Sarah’s father a long-lost sibling to one of the aforementioned five people in Ernest’s family tree? Either way would make Ernest and my mother 3rd cousins-once removed.  Can I figure this one out? How? Despite the challenges at hand, Ernest’s connection has given me a potential area in North Carolina where Polly or Grandma Sarah’s father probably came from.


UPDATE (11/1/2013): The ultimate DNA proof has been found.

Ernest is in fact related to my mother and me through her paternal grandmother, Sarah Partee Reed. This was confirmed from my cousin Caronde Puryear’s DNA results on Gedmatch.  Caronde Puryear is the granddaughter of my mother’s paternal first cousin, Armentha Reed Puryear.  My mother’s father, Simpson Reed, and Cousin Armentha’s father, Pleas Reed, were the sons of Sarah Partee Reed.  Grandma Sarah passed her X-chromosome to all of her children.  Her sons passed that X-chromosome to their daughters. 

According to Gedmatch, Caronde shares a total of 179.1 cM across 8 segments with my mother, who is her first cousin-twice removed. Caronde also matches my mother and me on our X-chromosomes at the following locations below in the charts.  Ernest, my mother, and me all match on the same spot on the X-chromosome, from 128.9 to 142.7 (21.2 cM).  This area on our X-chromosome falls within the areas where my mother and I match Caronde, which is highlighted in yellow. 

As males, Ernest and I only have one X-chromosome that came from our mothers.  Therefore, since Ernest and Caronde both match me in the same area on that X-chromosome, I can thereby conclude that Ernest and Caronde would match each other, and we are related to Ernest through Grandma Sarah and one of her parents. 

Caronde and my mother

Chr
Start Location
End Location
Centimorgans (cM)
SNPs
X
55,754,985
68,138,546
3.2
390
X
121,993,670
126,664,108
7.4
574
X
126,687,974
133,541,438
5.3
711
X
133,559,169
140,874,844
14.9
995
X
142,696,569
148,575,315
12.4
923
X
148,644,876
154,551,755
14.0
942

Caronde and me

Chr
Start Location
End Location
Centimorgans (cM)
SNPs
X
121,993,670
126,664,108
7.4
574
X
126,687,974
133,552,216
5.3
716
X
133,559,169
140,760,647
14.4
970
X
142,727,036
154,551,755
26.3
1,870

UPDATE (09/18/2014): Via Gedmatch, Ernest matches Caronde on the X, as concluded above.

Chr
Start Location
End Location
Centimorgans (cM)
SNPs
X
128,440,445
140,758,133
18.9
1453

“Few slaves escaped the pain of forcible separation from their kin, especially during the nineteenth century. The spread of cotton cultivation across the Lower South resulted in the removal or sale of some one million slaves from their homes in the seaboard states, deeply disturbing the civilization that black people had established in the aftermath of their forced exodus from Africa.”Dr. Ira Berlin, University of Maryland, from Families and Freedom

4 comments:

  1. It's great when we can narrow down relationships like this. Great work!

    ReplyDelete
  2. This is such great research Melvin!

    ReplyDelete
  3. Great discovery. I'm challenged by numbers, how did you determine the percentage of shared X DNA and the percentage of shared DNA across several chromosome segments?

    ReplyDelete

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