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, just a dozen years ago, 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 off of 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, Melungeon, 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.

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.  Both Family Tree DNA and 23andMe 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, does NOT provide this capability and is deficient in other matching tools, providing no chromosome mapping or comparison capabilities, leaving customers significantly in the dark as compared to the tools at Family Tree DNA and 23andMe.  Autosomal tests also provide an estimate of percentages of ethnicity.  23andMe only uses 3 population groups, European, African and Asian, while Family Tree DNA uses significantly more.  Ancestry reports erroneously high Scandinavian numbers for many people with no Scandinavian ancestry, so be somewhat leery of their ethnicity projections.

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.  At this point, both Family Tree DNA and 23andMe include X raw data in their downloads.  Only 23andMe shows matches specifically on the X chromosome although Family Tree DNA is planning to release this functionality.  Ancestry does not include any X matching or data, so you cannot use the X chromosome information in any way if you have tested at Ancestry.  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.

76 thoughts on “4 Kinds of DNA for Genetic Genealogy

  1. Roberta,

    I’m starting to get a lot of DNA questions on some of my genealogy lists. This article in particular would answer a question posting just today. How can I direct people to receive your DNA Blog?

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  7. Your assertion about AncestryDNA not having X data is incorrect. AncestryDNA does not do anything with it, but I have downloaded my data and the X data is there. I uploaded to Gedmatch and can see all my X matches.

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  16. I have done the MtDNA with Genographic Project and uploaded it to FTDNA. Iwould now like to upgrade but am not sure which one to get done. if I upgrade to the Full DNA test, does that include all 4 of the DNA groups you listed above, with results for ethnicity, cousins and X factor?

    • The X and autosomal is one test called the Family Finder. You can upgrade to the full mitochondrial sequence for the maternal line. If you are a female, you can’t order any of the Y tests. So, no, the tests are separate except for the X and autosomal.

  17. Hi, I hope you can help me. My mother and bio father were first cousins. They never married and were estranged. He is dead now, but he had my half-sister with his third wife. She found me on Ancestry last year and we have been communicating, but she and her mom’s family don’t believe that we share the same father. Is there a DNA test that I can take that will show the common ancestors first cousins would indicate? My sister and I are separated by 2000 miles and are amicable, but she isn’t willing to pay for a DNA test, but I want to remove any doubts of my veracity.

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  20. Is there a difference between a court appointed DNA and your DNA to see if you are the father of a son? This test was taken approx. 18 years ago.

    • The tests 18 years ago were very different than the tests today. They would have been a small number of CODIS markers, probably 15. It would be the interpretation of the results you would be interested in.

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  23. I am one of the people whose results from Ancestry showed Scandanivian DNA (the largest group) but have no Scandinavian ancestors. Would it be helpful to take another DNA test from a different company to verify or disprove this.

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  25. I was adopted and have no knowledge of my biological father and no confirmation of my biological mother(who is deceased), however, I found someone who I think is her son. I have done 23 and me, I am female. I have encouraged this person, who I think is my brother, to do it as well. Am I correct that his results will indicate whether we are siblings? Even if we have different fathers?
    On a separate note, how useful is 23 and me going to be in helping me discover my biological father and his roots? So far, it s a long list of far off relatives. It’s quite bewildering.

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  30. You can transfer your AncestryDNA to FTDNA and view X chromosome matches.

    FTDNA offers a free autosomal transfer of your raw data from Ancestry.DNA. Once your data is in the FTDNA system you can view your top 20 matches and tell if you share segments on the X chromosome. You can even use their chromosome browser to see where you match on each chromosome, including the X. To unlock the full feature set inducing the ability to contact your matches you can recruit others to transfer or pay a nominal fee.

    There is no obligation. Please use this link if you want to try this. Make sure to copy the entire link on both lines and paste into your browser:


    Good luck!


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      • If the hair sample doesn’t have the root, but was a cutting, would the same prediction apply? Should I hold it and hope it can be analyzed in a few years?
        In my case, it is my grandfather’s hair, from 1940; I would like to know his mother’s mtDNA haplogroup. The hair was undoubtedly handled by a family member, though, such as his wife or my mother. I do know their mtDNA haplogroup.

      • Thank you! I believe it’s in the original wax paper at the moment, so I’ll check and move to a paper envelope if the wax paper is a problem.

      • Got it. Thanks so much. Love your blog, always look forward to your posts.

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  37. I know my maternal ancestory back a few generations,but want to know if Khazar,Ashkenazie,Sefardic roots are there.I am female.My family came from Poland,Belarus and possibly Italy and are all jews.My Polish side look Mongol. There were many tribes in history. My Y side is the one I dont know past 2 generations.No males to test.What test should I use? I am a second generation female Jewish American.

  38. My mother is 90 years old and was adopted. Her adopted mother refused to tell her anything about her bio parents. I am new to genealogy and don’t know the terminology used in the FTDNA results or what anything means. Where I can I go for help to explain and answer questions?

    • There are lots of avenues. The Family Tree DNA webpages have some help and they have a learning center. I do reports for both Y and mtDNA. There are lots of articles on this blog, plus I’ve listed books as well. Diahan Southard does a one hour “test drive” of your results too. So there are lots of ways to learn.

  39. Hi. A 2nd half cousin and I are trying to see if theirs a test to fine if we are really whole 2nd cousin. We have reason to believe that my Great Grandfather on my mother side is going to be his Grandfather on his fathers side. And hes the last of the 1st cousins,

  40. I do not know who my mother was. Found out in my 30’s that my parents weren’t really my parents. Believe my father to actually be my grandfather and my mother who has passed away to be my 1/2 sister. she had three other children and need to know if a dna will tell me and her daughter if we are 1/2 sisters and which test would be the best to use. Parents that raised me are deceased and so far have not been able to find any one alive to help. I am 71 and her daughter is 61.

      • I know I was not adopted formally. My father was actually my grandfather raising a baby from one of his two girls. during the time I was born the children had been removed from the home and placed in Baptist childrens home and they say because of hepa laws they can not give me any info. had I been adopted I could have gotten death certificates or they say they could get them and then they could have released info. But now it seems as though my only option is dna with the person I believe to be my half sister or I could do it with her brother who I believe to be my half brother. Sorry I didn’t explain well the first time. I did go look at the site you provided but it still only applies to adoptions. When I was 18 months old the parents that raised me filed for a birth certificate listing them as my parents and saying I was born at home and they were just getting around to filing for birth certificate. Later I learned I was born at st lukes hospital but that doesnt help me because I have no idea what name birth mother used for me. I was told my father(grandfather) named me after his youngest daughter who was adopted out before he was able to get his other 4 children back. So, is possible for you to tell me which test or tests could possibly help me and if sister or brother would be a better person to compare to

      • DNAAdoption does not just deal with adoption, but with helping people of unknown parentage discover their roots. Whether the adoption was legal or not is of no consequence. The situation you described where the grandparent may also be the parent is too close genetically for a cut and dried answer. You either need to work with them or a have a private consult.

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  43. A few weeks ago, my mother told me that my “dad” was not really my father. I am currently 20 years old and have a deep desire to find my biological father. She gave me his name, which I searched on the internet. Though, he is nowhere to be found. She did not really know him too well. Therefore, she knows nothing about his family. I am awfully frustrated and don’t have a clue where to start. I was wondering if the Family Tree DNA could help me in this case.

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