Ancestral DNA Percentages – How Much of Them is in You?

One of the most common questions I receive, especially in light of the interest in ethnicity testing, is how much of an ancestor’s DNA someone “should” share.

The chart above shows how much of a particular generation of ancestors’ DNA you would inherit if each generation between you and that ancestor inherited exactly 50% of that ancestor’s DNA from their parent. This means, on the average, you will carry less than 1% of each of your 5 times great-grandparents DNA, shown in generation 7, in total. You’ll carry about 1.56% of each of your 6 times great-grandparents, and so forth.

As you can see, if you’re looking for a Native American ancestor, for example, who is 7 generations back in your tree, if you carry the average amount of DNA from that ancestor, it will be less than 1% which will be under the noise threshold for detection – and that’s assuming they were 100% Native at that time.

Everyone inherits 50% of their DNA from their parents, but not everyone inherits half of each of their ancestors’ DNA from a parent. Sometimes, the child will inherit all of a segment of DNA from an ancestor, and in other cases, the child will inherit none. In some cases, they will inherit half or a portion of the DNA from an ancestor. In reality, the DNA segments are very seldom divided exactly in half, but all we can deal with are averages when discussing how much DNA you “should” receive from an ancestor, based on where they are in your tree.

The generational relationship chart above represents the average that you will inherit from each of those ancestors. Of course, few people are actually average, and you may not be either. In other words, your ancestor’s DNA may not be detectible at 5, 6 or 7 generations, because it was lost in generations between them and you, while another ancestor’s DNA is still present in detectable amounts at 8 or 9 generations.

How Does Inheritance of Ancestral Segments Actually Work?

For you to inherit a particular segment from one GGGGG-grandparent, the inheritance might look something like this. “You” are at the bottom of the tree. You can click on any graphic to enlarge.

In the above example, you inherited one tenth of the segment from your GGGGG-grandparent which was one third of the DNA that your parent carried in that segment from that ancestor.

A second example is every bit as likely, shown below.

In this second scenario, you inherited nothing of that segment from your GGGGG-grandparent.

A third scenario is also a possibility.

In this third scenario, you inherited all of the DNA from that ancestor as your parent.

Now, think of these three scenarios as three different siblings inheriting from the same parent, and you’ll understand why siblings carry different amounts of DNA from their ancestors.

Of course, the child can only inherit what the parent has inherited from that ancestor, and if that particular segment was gone in the parent’s generation, or generations before the parent, the child certainly can’t inherit the segment. There is no such thing as “skipping generations.”

In this fourth scenario, the parent didn’t receive any of the segment from the GGGGG-grandparent, but maybe their brother or sister did, which is why you want to test aunts and uncles. Testing everyone in your family available from the oldest generation is absolutely critical.

This, of course, is exactly why we test as many relatives as we can. Everyone inherits different amounts of segments of DNA from our common ancestors. This is also why we map our matching segments to those ancestors by triangulating with cousins – to identify which pieces of our DNA came from which ancestor.

Seeing examples of how inheritance works helps us understand that there is no “one answer” to the question we want to know about each ancestor – “How much of you is in me?” The answer is, “it depends” and the actual amount would be different for every ancestor except your parents, where the answer is always 50%.

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19 thoughts on “Ancestral DNA Percentages – How Much of Them is in You?

  1. Thank you
    My question is , does FTDNA use a tringulation method to give the matches indicated ( be it ydna or mtdna) and if not, why not, and what method do they use?

    kind regards

    • Triangulation, by definition, has to include the identification of ancestors. So by that definition, no. However, when you connect your DNA to your tree and the DNA of your relatives to them in your tree, then the matches that they designate as paternal or maternal are indeed, utilizing the matching DNA segments of both you and those other people – so in this way, yes.

      • Thanks

        So , I have connected my tree . This gave me 2 x 4th cousin matches on my maternal side ( respec. 107cm ( daughter ) and 177cm ( mother )) and we match on my tree between the years 1780 to 1800. Since this is correct via registry records is it not too far back in time for a score of over 100cm segment matching?
        It seems that the division of ones ancestors for oneself must be not exacting in percentage.

        warm regards

  2. My maternal grandmother tested with Ancestry last year, and I was very surprised at how low our match was (1348 cM, according to Gedmatch). This showed me that the inheritance of DNA can be haphazard indeed beyond the parent/child relationship. I estimate that I share around 19% of my DNA with her. She has a parent/child match to my dad, and I have a likewise match to him.

  3. This article should be a lesson and reminder for everyone to make an effort to atDNA test your elders, including grandparents, parents, and aunts and uncles. Glancing at all the charts, you can see how testing an elder can gain you additional generations of matches. I will be forever grateful that my 83 year old uncle agreed to test, and have me administer his results. My uncle’s DNA matches at Ancestry have been a significant factor in breaking down walls in our shared lineages.

  4. Thank you for the explanation of how DNA is/is not passed on through succeeding generations. I had a male 1st Cousin, Once removed (one of two brothers, the last males in the line of my Grandfather and their Great Grandfather) tested through FTDNA. I had to drop the search criteria to 300 SNPs / 3 cMs to find any matching DNA between us. He actually had more DNA in common with my 2nd Cousins (his 2nd Cousins, once removed) who had also tested at FTDNA, than he did with me. I guess I just got more of my Mother’s DNA, than I did my Dad’s. Eileen Miller

    On Tue, Jun 27, 2017 at 12:15 PM, DNAeXplained – Genetic Genealogy wrote:

    > Roberta Estes posted: “One of the most common questions I receive, > especially in light of the interest in ethnicity testing, is how much of an > ancestor’s DNA someone “should” share. The chart above shows how much of a > particular generation of ancestors’ DNA you would inh” >

  5. Thanks for the interesting article. I was surprised to learn that I have about 1% of East African according to My Origins 2.0. My Origins 1.0 reported 3% North African DNA while My Origins 2.0 didn’t report any North African (Middle Eastern) or Sephardic DNA.

    Gedmatch confirmed that I have 1-2% of East African DNA and 3-4% of North African JEWISH DNA. In fact, the Gedmatch admixture utilities overemphasized the ancient Sephardic ancestry and assumed in some cases I was an Italian Jew. I’m curious about which of my long-lost relatives might be carrying those genes from SW Europe and Africa. My known ancestry is Eastern European Jewish.

    Karen Smith

    • Your DNA would still be divided in half, but you could be expected to retain more of the original ancestor’s DNA than otherwise. It makes it more complex, that’s for sure – but on the other hand, you also retain more of the original ancestors because you have more than one line to them.

  6. There is a slightly different perspective between total DNA and individual segments of DNA. Each segment is rarely divided close to half way – each segment can be divided into anything from 0/100 to 100/0, and wild swings are often seen. The total amount of DNA from an Ancestor (the sum of all segments) will tend much more toward 50/50, or somewhat closer to that. And the deviation from the nominal can grow in either direction. For instance if you got 23% of your total DNA from your paternal grandfather; you had to get 27% from your paternal grandmother.

  7. Wonderful post Roberta!
    For those of you interested in how 4 generations of inheritance look in practice, I did a chart for a group of my Norwegian cousins who have 4 generations tested. Interestingly a whole chromosome stayed intact all the way to a great granddaughter (chr 22) and another was almost all there (chr 6)
    http://blog.kittycooper.com/2014/05/etne-endogamy-and-four-generations-of-dna-for-my-norwegian-descended-cousins/
    Plus Angie Bush also has 4 generations tested, again 2 chromosomes remained intact see
    http://blog.kittycooper.com/2014/09/using-the-chromosome-mapper-to-make-a-four-generation-inheritance-picture/

  8. Pingback: Ethnicity and Physical Features are NOT Accurate Predictors of Parentage or Heritage | DNAeXplained – Genetic Genealogy

  9. Hi, I am a male who was born in Egypt to Egyptian parents, but my dad tells me he probably had an ancestor from somewhere around Turkey, he believes it could be Armenia. She/he may have immigrated to Egypt during the Armenian genocide in the early 1900’s. My mom also tells me she may have a Turkish ancestor. I wouldn’t be surprised if that is true. My grandmother on my dad’s side was so fair you would never tell she was Egyptian (she was born in Egypt though and her parents were also born in Egypt). Long story short, I’m dying to find out where the hell my ancestors came from (as even myself, I am too fair-skinned compared to the average Egyptian). I bought a 23andme kit from Amazon, then bought the LivingDNA kit when I found out it can show you the maternal and paternal lineage. I intended to return the 23andme kit. Now I read that LivingDNA works best if you have mostly British ancestry (which I definitely don’t). So which test do you recommend? Thanks!

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