4 Kinds of DNA for Genetic Genealogy

There seems to be a lot of confusion about the different “kinds” of DNA and how they can be used for genetic genealogy.

It used to be simple.  When this “industry” first started, in the year 2000, you could test two kinds of DNA and it was straightforward.  Now we’ve added more DNA, more tools and more testing companies and it’s not quite so straightforward anymore.

Here’s a basics primer.

1. Y-line DNA – tests the Y chromosome which is passed from father to son, along, in most cases, with the surname.  Only men can test for this, because only men have a Y chromosome, leaving female genealogists with Y chromosome envy, having to go and beg their fathers, brothers, uncles and male cousins to test for the surnames in question.  We compare the results of the Y chromosome test between males to see if they match and are related in a genealogical timeframe.  We also obtain the haplogroup which defines deep ancestry, such as European, African, Asian or Native American.  Surname, haplogroup and other interest projects (such as Acadian, American Indian, Cumberland Gap, etc.) exist for both Y-line and mitochondrial DNA at Family Tree DNA.  These projects are indispensable for both genealogy and genetic genealogy research.  Family Tree DNA is currently the only testing company that offers this these tests.

2. Mitochondrial DNA – is passed from mothers to both genders of her children, but only passed on by females.  Males carry their mother’s mitochondrial DNA (mtDNA) but they don’t pass it on.  We compare mutations to see of people share an ancestor in a genealogical timeframe, but because the surname changes in every generation, it’s more difficult genealogically to make the connections.  The lack of a central data base prevents people from being able to determine if others from the same genetic line have already tested.  For Y-line, surname projects and surname matches provide this function.  Mitochondrial DNA testing also provides a haplogroup which defines deep ancestry, such as European, African, Asian or Native American.  Family Tree DNA is the only commercial company to offer full sequence testing which is sometimes necessary to determine whether a match is really genealogically relevant.  When testing the HVR1 or HVR1 and HVR2 regions only, meaning the participant did not purchase the full sequence test, Family Tree DNA doesn’t just “estimate” haplogroups, but runs a panel of 22 SNPs to accurately assign a haplogroup for the participant.

The paths of inheritance for both the Y-line, blue, and the mitochondrial DNA, red, are shown below.  If you’d like more specific information about how this works, with some examples, you can download the paper, DNA Testing for Genealogy – the Basics, from my website, www.dnaexplain.com under the Publications tab.

3. Autosomal DNA – tests the rest of the DNA provided by both parents on the 23 chromosomes, not just two direct lines, as with Y-line and mitochondrial DNA.  Older tests of this type tested between 21 and about 300 markers, but current generation testing provided by Family Tree DNA (Family Finder test), 23andMe and AncestryDNA test use about 700,000 locations and are in an entirely different category in terms of their usefulness and accuracy to genealogists.  These tests provide a list of cousins from all of your lines, but it’s up to you to figure out how these cousins are related to you.  The testing companies provide different tools to help in this quest.  All three companies provide the ability to download your raw data results so that you can do further analysis personally and by using several online tools, the most popular being GedMatch.  AncestryDNA, the autosomal test through Ancestry.com, is deficient in  matching tools, providing no chromosome mapping or comparison capabilities, leaving customers significantly in the dark as compared to the tools at Family Tree DNA,  23andMe and GedMatch.  Autosomal tests also provide an estimate of percentages of ethnicity.  In 2015, 23andMe began a process of redesigning their website and products to go along with their new FDA compliance and focus on selling DNA to medical research partners, to the detriment of genetic genealogy.  Previously existing features are gone and the price has doubled, effectively removing 23andMe as a viable player in the genetic genealogy arena.

The inheritance paths for autosomal DNA are shown below.  You can see that this includes all of the various ancestral lines, including the lines that contribute the Y-line and mitochondrial, but those are separate and different tests providing different kinds of information.

4. The X Chromosome – has special inheritance properties that allow people to use these results separately from the rest of the autosomal results, although the X chromosome is a part of the 23 sets of chromosomes used for autosomal testing.  The inheritance paths are different for males and females, because males only inherit an X chromosome from their mother (and a Y from their father which makes them male), but women inherit an X from both of their parents.  I show these charts and discuss how to use the X Chromosome for genealogy, giving two examples, in my blog posting, X Marks the Spot.  The best way to functionally use the X information is to diagram your family lines that contributed to your X chromosome using your pedigree chart and Blaine Bettinger’s charts, found in my blog (and his previously) and upload your results to http://www.GedMatch.com.  GedMatch provides X chromosomal matching utilities along with lots of other DNA analysis and comparison tools.  GedMatch is free, but donations are encouraged and appreciated.

106 thoughts on “4 Kinds of DNA for Genetic Genealogy

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  7. this article was written in 2012, but I just completed my test with AncestryDNA (2015) and the raw chromosome results I received (after downloading to FtDNA and GEDmatch) includes X chromosome segment matches. Can I assume that this means that AncestryDNA now includes this in their tests? The most interesting thing about my results in general is that there are a dozen or so names in there of Russian origin although I had no DNA identified as coming from that region, I have matches, including the X chromosome, with several that appear to have both Russian and Finnish ancestry (a regional grouping on AncestryDNA).

      • I, too, noticed that my AncestryDNA test (taken this year) included 25 chromosome segment matches, which I presume must include my X (chr. 24) and Y (chr. 25) chromosomes. (The segments included for chromosomes 24 and 25 number only in the hundreds, compared to the other segments which number thousands per chromosome)
        Can these Y chromosome segment matches from AncestryDNA be mapped to FTDNA’s Y-DNA test, and/or into GEDMatch.com for Y-DNA testing? All that Ancestry provides is an RS number and length for each segment, they don’t identify them using the DYS coding.

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  9. I want to find if I have cherokee in my lineage, I have been told that I do on both my mother and father. Is there a dna test that can shoe me this?

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  13. I have tested with Ancestry.com and received the results. Amazing discoveries about Native American heritage, Irish, European West, etc. As a result, I am hooked and now trying to learn more about DNA and genealogy in general. I most recently tested with National Geographic and am awaiting those results. Question: Is the Family Tree DNA test the same or different than Nat Geo’s?

  14. I am related to a woman through two lines, 3rd cousins on one and 5th cousins on the other. I show a dna match to her but I do not show a dna match to either of this woman’s daughters or her daughters’ children. Is this possible?

  15. Hi

    Can you give me some help on the best way my Grandmother can find out who her father wae. She is 87 years old and her mother (my Great Grandmother) never told her who her real father was (my Great Grandfather). She basically told her it wasn’t her place to know and took this info to her grave! My Grandmother has always wanted to know who he was and of course if she has any other family connected to her but without any info at all, the only chance she has is potentially through DNA. My Grandmother is still alive and I have spent months trailing through forums and help articles and cannot seem to get the answer I am looking for. All I need to know is if my Grandmother provided a saliva/blood sample, is there even a slight chance that we could find out who he was? I appreciate he will be dead however maybe if he had a family, could DNA link us to them? I am desperate to find this out as my family tree will never be completed until I know this and just want to at least try and find out. I know its a very long shot but as a desperate 35 year old I would love to give my Grandmother this before she is taken from us. Any help or guidance would be very very very much appreciated as I am so confused as to where to start.

    Thank you

  16. I have a problem similar to Wendy’s. I’ve been tested at both FTDNA (Y-67 and mtDNA). I had my mother (who is 96) take the Autosomal test at Ancestry, and I likewise had an Autosomal test at Ancestry. The results are confusing, leading me to believe that my “German” great, great grandfather on the maternal side either wasn’t German (or who he said he was) or, more likely, he wasn’t the father of my maternal grandmother, my mother’s mother. Which of the FTDNA tests should I have my mother take so that we could try to solve this mystery? Roberta, your site and blog are hugely educational and entertaining – thank you for your commitment to this work!

    • I hope you’re not using ethnicity results to reach that conclusion. If you want some professional help with this, I can do a referral. The mystery will be solved by who you match that is descended from that great-great-grandfather. If you haven’t had the Family Finder test done on your mother at FTDNA, order that too. You want her autosomal results to be in both data bases.

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  18. My son took both the Y-DNA (67 plus special markers) and the full mt-DNA test at Family Tree DNA. He did not take the Family Finder test. It is the mt-DNA test that concerns this email. I understand the difference between mt-DNA and the x chromosome and how each are transferred to descendants. What I really want to know is how Family Tree DNA is giving my son exact mt-DNA matches from people who only took the Family Finder test?

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