Follow the “X”

By Don Taylor

Image by Caroline Davis2010 (CC BY 2.0)

Twenty-Two of our chromosomes are recombinant in nature, which means you receive 50% of your mother’s DNA and 50% of your father’s DNA.  The 23rd chromosome, the X-Y or X-X, is quite different. If you are a male, you received a “Y” chromosome from your father and you received an “X” chromosome from your mother. That X is a recombinant, in that it consists of 50% of your mother’s DNA. However, if you are a female, you received 50% from your mother as recombinant from her, but you also received your other X chromosome as a duplicate from your father. The effect of that is that the amount of DNA received from an ancestor through your X chromosome is higher if the ancestor path switches gender every generation. For example, my mother received 50% from her mother and 50% from her father. Her father received 100% of his X DNA from his mother (recombinant).

Blaine Bettinger (The Genetic Genealogist) has an excellent article, “More X-Chromosome Charts,” which provides charts showing both the Ahnentafel numbers and the percentage of X-DNA you received from which ancestors. The effect of this switching back and forth is that a male receives 12.5% of his mother’s father’s mother’s father’s mother’s father’s mother instead of the 0.78% that he received from that ancestor (a 5th great-grandmother) in the other 22 chromosomes.

I call that line a “zig-zag” line because it shifts gender every generation can provide insight into genetic connections that can really help in understanding matches and where you and that person may have a common ancestor.

The following are my “zig-zag” ancestors:

Ahnentafel #PersonSexExpected %
of X-DNA
3My motherF100
6Richard Earl Brown (1903-1990)M50
13Mary Elizabeth Manning (1878-1983)F50
26John William Manning (1846-1888)M25
53Minerva Ann Tolliver (1821-1902)F25
106Tulion Tolliver (unknown dates)M12.5
213Unknown 5th great-grandmotherF12.5

 In any generation you follow a woman’s mother, the expected % of X-DNA is cut in half. So my mother received 50% of her X-DNA from her mother. I have 50% of my X-DNA from my mother’s mother, so a similar “zig-zag” chart for my mother would be:

Ahnentafel #PersonSexExpected %
of X-DNA
3My motherF100
7Madonna Mae Montran (1893-1976)F50
14John Montran (c.1867-c.1897)M25
29Unknown 2nd great-grandmotherM25

Because my great-grandfather, John Montran’s life is such a mystery and because his parents are a complete mystery to me, discovering ancestors with whom I share X-DNA with may provide key insight into potential candidates for John.

If you share any of the above ancestors with me, I’d love to hear from you and try compare our matches in order to learn of our common ancestor. 

DNA Testing and Results Companies

23 and Me requires you to compare DNA in their browser and then manually determine if there is a match on the X-Chromosome. You can download your raw DNA data and import it into several other services. (Kits available for $69 until 23 Nov 2018)

AncestryDNA doesn’t provide information about X-DNA Matches nor does it provide for a chromosome browser. You can, however, download your raw DNA data and import it into FamilyTree DNA and GEDMatch. (Kits are available for $59 until 21 Nov 2018)

FamilyTree DNA shows you that an individual has an X-Match with you, even if that match is extremely low, even down to 1cM if they match otherwise at higher levels. You can test with FamilyTree DNA, with “Family Finder.” Alternately, you can also upload raw DNA results from Ancestry, 23andMe, MyHeritage and the National Genographic Project 2.0. (Kits are $79.00)

GEDMatch allows you to select whether a match is based on autosomal or X. By selecting X, you can see only those matches with whom you share X-DNA. If you look at the individual’s kit number and it begins with “A” they kit was imported from Ancestry. GEDMatch does no testing but allows you to upload your raw DNA data from various services including Ancestry, FTDNA, WeGene, MyHeritage and others. GEDMatch does no testing,

MyHeritageDNA does not show you your X-Matches (at least not with uploaded kit results).

LivingDNA does not show you any match data.

Looking solely at X-Chromosome match capability,  FamilyTree DNA and GEDMatch are the best, with 23 and Me following closely behind. AncestryDNA, Living DNA, and MyHeritageDNA do not support X-Chromosome match analysis. Look closely at your tree and your X-Chromosome, you may find that a new clue to help find that elusive ancestor.

————–  Disclaimer  ————–

DNA, the X Chromosome & Minerva Tolliver Manning

For many years, I have been hearing the stories that my 3rd Great Grandmother, Minerva Tolliver Manning was “Full-Blooded Cherokee.” I’ve never believed it and have written about the possibility of Minerva being Native American a few times before. Please see:


Ever being the skeptic, I considered that my grandmother had really gotten pregnant from a different man other than whom she said was the father. She was apparently estranged from her husband at the time of her pregnancy and anything is possible. (She never suggested that her husband was the father.) If the man she always said was the father actually was, then my mother’s half-sister will show the same genetic information on their X-chromosome.

My half-aunt was tested and sure enough, they are half sisters, which we expected. What is really cool is that for a person’s 22 chromosomes they are a mix of each of their parents, however, for the 23rd chromosome, the XX, a girl receives one X from their mother and one X from their father. The mother’s X is a blend of her parents but the father’s contribution is passed on with little to no change. That means that if two girls share the same father then one of the X chromosomes is identical between the two girls. My mother and my half-aunt share one X exactly, so we know, beyond any doubt, they share the same father.

Person
Name
% contribution atDNA
% cont. of X Chromosome
Individual
Mom & Half Aunt
100%
100%
Father
Clifford/Dick
50%
100%
Grandmother
Mary Manning
25%
50%
Great-grandfather
John W. Manning
12.5%
50%
2nd Great-Grandmother
Minerva Tolliver
6.25%
25%
3rd Great-Grandfather
Tulion Tolliver
3.125%
12.5%
As you can see from
the above table, a person’s 2rd Great-Grandmother provides four
times the contribution to an X chromosome than to the normal atDNA
contribution. If Minerva was full-blooded Cherokee as family history says then,
alternating sex through generations, her 2nd great-granddaughters should
have about 25% Native American contribution. Not there.  According the test results from 23 & Me,
their identical X-chromosome shows no Native American contributions.  
What is very interesting is that although both my mom and my
aunt are over 99% European, there is a .2% Sub-Saharan contribution overall and
it is on the X chromosome.  Looking at
only the shared X chromosome it appears to be between 4% and 6% of the X contribution.
That would be in keeping with a 4th or 5th Great-Grandparent’s
contribution.  If Minerva were ¼ to 1/8th
Sub-Saharan African, she would have had about the right percentage to “pass” as Native
American.  From the DNA evidence that
appears to me to be much more likely of a scenario than for Minerva to have
been Cherokee.
My Mom’s X results
My Aunt’s X results



 

Future Activity
As the saying goes, a mother knows her own children, but fathers can be a surprise. As such, I’m confident that Clifford/Dick was Mary’s child. I am also confident that Enoch and Minerva believed that Mary (and her sister Phoebe) were their granddaughters. Mary and Phoebe were orphaned and Enoch and Minerva raised them for a while.

Although reasonable and likely, there is always a possibility that someone else jumped into the mix. I know next to nothing about Mary’s parents, John William Manning and Eliza Jane Fannin. It is always possible that John William Manning wasn’t Mary’s father. Mary had a half brother, Robert, but we are not certain if he was John’s child or Eliza’s child who took on the surname of Manning. In either event, I don’t believe that line will provide much in the way of proof. Rather, Minerva had five daughters, Nancy Ann, Sarah Jane, Mary Ermaline, Grisella, and Prudence Manning. Their female descendants will have the mtDNA that would show Native American ancestry if Minerva were, in fact, Cherokee.

I’ll continue research for the descendants of Minerva and see if any of them are interested in testing, but as things sit currently, I am confident that Minerva was not Native American.