Concepts – “Who To Test?” Series

I often receive questions about who to test to obtain (discover) the Y or mitochondrial DNA of a particular ancestor in one’s tree. The question often arises when people are attempting to find either Y or mitochondrial DNA to confirm that an ancestor descends from or belongs to a particular population.

For example, “My great-great-grandmother was supposed to be Cherokee.  How can I tell if she was?”

The answer would be that if she was Cherokee on her mother’s direct maternal side, testing the mitochondrial DNA of specific descendants would yield the answer.

Regardless of origins, the concept and techniques apply to everyone. People of Native American, African, Jewish, European and Asian heritage carry specific haplogroups and match people who have similar roots.

You may want to read this short article, 4 Kinds of DNA for Genetic Genealogy to understand the difference between Y, mitochondrial and autosomal DNA, what testing can tell you, and how they can help your genetic genealogy.

At a very basic level:

  • Y DNA testing tests the direct paternal (typically surname) line only, for males only. The Y chromosome is only passed from fathers to sons, so it is not divided nor mixed with the mother’s DNA. Females don’t have a Y chromosome, which is why they can’t test.
  • Mitochondrial DNA testing tests the direct matrilineal line only, for everyone, males and females both. The mitochondria is passed from mothers to all of her children, but is only passed on by females. It is not mixed with the father’s DNA, so it is not divided during the inheritance process.
  • Autosomal DNA testing tests all of your DNA, providing cousin matches and ethnicity estimates – but does not provide you with specifics about any individual line. You inherit half the autosomal DNA of each of your parents, so ancestral DNA diminishes by half in each generation. Autosomal testing is a great overview of all of your DNA lineages, but can’t tell you where any particular line comes from.

Testing the appropriate descendants of each ancestor allows us to build a DNA pedigree chart in order to determine the proven, specific heritage and origins of each individual line.

Here’s what my DNA Pedigree Chart looks like through my 8 great-grandparents where I’ve successfully obtained the Y and mitochondrial DNA of their descendants. Y and mitochondrial DNA, of course, has special properties and reaches back hundreds and thousands of years in time, because the Y and mitochondrial DNA is not diluted by the DNA of the other parent during inheritance.

I’ve converted the relationships in my pedigree chart above to an Ancestor Pedigree Chart, below, because we will be working with each individual and adding lines for other family members as we determine who we can test. You can click to enlarge the image.

In the Ancestor Pedigree Chart, shown above, there are 16 different people who all carry mitochondrial DNA, representing 8 different mitochondrial lines. Mitochondrial contributors, all women, shown in pink both carry and contribute mitochondrial DNA. Mothers contribute their mitochondrial DNA to the males, shown by pink hearts, but the men don’t pass it on. The daughters pass their mitochondrial DNA to all of their children.

There are 8 people, shown in blue, who carry and contribute Y DNA, representing 4 different Y lines.

Each mitochondrial and Y line of DNA has a story to tell that can’t be told any other way. Autosomal DNA does not provide specific information about the genesis or ethnicity of any particular line, but Y and mtDNA does. If you want to know specifically where, what part of the world, or what clan that particular ancestor descended from, Y and mitochondrial DNA may tell you.

The question becomes, who can be tested that is living today to obtain that specific information about each particular ancestor.

Of course, the answer of who to test to find the ancestral Y and mitochondrial DNA varies depending on the gender of the person, and where they are located in your tree.

If the person in the tree is no longer living, the answer about who to test may hinge on their siblings, and the descendants of their siblings or maybe cousins. Or perhaps you’ll need to go back up the tree a generation or two to find appropriately descended relatives to test.

For each of the individuals in this tree, I’m going to answer the question of whom to test to obtain their Y and mitochondrial DNA – and how to find a suitable candidate. Talking them into testing, however, is all up to you:)

If you haven’t tested your Y or mitochondrial DNA, and you want to, you can order those tests at Family Tree DNA.  I suggest a minimum of 37 markers for Y DNA. You can always upgrade later to 67 or 111 markers.  Regardless of your testing level, you’ll receive haplogroup estimates, matches and other information.  For mitochondrial DNA, order the full sequence test so you’ll receive your full haplogroup designation. Several Y and mitochondrial haplogroups originated in Asia, with some lines settling in Europe, some in Asia and some in the Americas – so you need as much information as you can extract from your DNA.

Please join me for the “Concepts – Who To Test?” Series – coming soon to a this blog, so stay tuned!!!



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28 thoughts on “Concepts – “Who To Test?” Series

  1. Thank you, Roberta, for your pink and white DNA chart with pink hearts added. It is illuminating. I finally get it :-).

    • It depends. I know that’s not what you wanted to hear. To find ethnicity, normally about 5-6 generations, but sometimes less and sometimes more. DNA is not cut exactly in half in each generation, so you may receive more or less of any ancestor’s DNA in any generation. Same goes for cousin matching. You will always match 2nd cousins or closer, often 4th cousins or closer, and sometimes more distant relatives too on segments that happen to be persistent for generations.

  2. Everyone recently interested in DNA testing for genealogy purposes should read this excellent explanation by the writer.

    • You should be able to download the raw DNA from Ancestry, transfer to FTDNA, then order the Y testing.

    • You may be able to get a basic look at your father’s Y-haplogroup from his Ancestry kit by following the instructions at:

      Ancestry datasets contain some Y-DNA SNP readings; they just don’t report them. I compared my ftdna Y results with Ancestry data mined as above…the reported haplogroup is well up (down?) the tree compared with ftdna since far less data is there in the Ancestry kit, but at least something can be salvaged. It is correct as far as it goes.

      • Thank you so much! Have you used that dna converter yourself? It says it could harm my computer, and I wonder if someone has used it and can verify it didn’t cause a problem with their computer.

      • I checked out the Promethease method (out of curiosity, to compare to better data I already have from ftdna) but I did not check the dna converter; the warning may be a virus filter being over-cautious but I don’t know for sure.

        If you sort the Promethease report by topics (drop down to Haplogroups) and Sort by Frequency (reversed) one arrives at a list of rs readings in individual boxes. The first few of these are probably otherwise unidentified and generally unhelpful. If you continue down several pages, the report will eventually get to one that specifies a haplogroup-defining reading (in my case, M258+, the root of the “I” haplogroup). It is then easier to switch to, go to the page for that haplogroup, and see what further readings define earlier branches. Then, the SNPedia numbers can be matched up to earlier pages of the Promethease report.

        Not simple, but better than nothing..

  3. I am an identical twin. My twin has tested her DNA, as has another sister. As far as ancestral DNA goes, would mine be any different. I realize changes happen over the 80 years since birth, but would the ancestral DNA change? The older sister showed more native American DNA than mine twin did. But I am thinking that coming from the same egg and sperm and having only one placenta involved ours would be the same.
    I’m looking to save some money here. Thanks.

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  7. I’m still overwhelmed by the testing options available. If I’m trying to identify my maternal-grandfather what is the best test to take?

  8. I’m trying to identify my Maternal Grandfather. What is the best test to take? What if there are no living sons or son’s of sons living?

    • If your mother or her siblings are alive, test them. Autosomal is your only choice at this point. I would then use the Leeds method to group matches.

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