Why Y?

Father’s day is always an occasion for the DNA testing companies to offer discounts on their kits and this year is no different. Give Dad a DNA kit is the message. Why should you? Well his autosomal DNA might find cousins you had lost track of, discover ethnicity you were curious about, or solve an unknown parent mystery. After all, he is one generation closer to your ancestors. I tested my late father long ago and am grateful to have that information. Click here for my evaluations of the different autosomal testing companies.

Dad and I in about 1953 (he was in the Air Force)

Only men have a Y chromosome and there are tests for just the Y. Those tests can give you information about your surname and your deep father line ancestry. Family Tree DNA is the place to test just the Y although both LivingDNA and 23andme will give you a high level Y haplogroup, plus there are tools to determine the haplogroup from an AncestryDNA or MyHeritage test (discussed at the end of this post).

If you know what a Y haplogroup is you can skip this paragraph … The 23rd pair of chromosomes is an XX for a woman and an XY for a man. The problem or benefit is that there is no second Y for that Y to recombine with. Thus unlike the other 22 chromosomes a man’s parents give him, the Y is unchanged from his Dad’s and his Dad’s and his Dad’s and so on, except for mutations. Those little changes accumulate over thousands of years and allow scientists to catalog the Y and trace the migration of mankind around the globe. Each set of Y mutations is assigned to a haplogroup, and subgroup, which can tell you where your ancestors came from thousands of years back. Here is the latest diagram from the
wikipedia article on Y

Y haplogroup world expansion – start at the big Y in Africa (A was the first haplogroup) -image from wikipedia by Maulucioni [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)]

If you are of European origin then click here for the Eupedia articles on each haplogroup.

My Norwegian Munson family is R1b rather than being the Viking I haplogroup. The R1b haplogroup is associated with the Indo-Euopean invasion of Europe. Since we have done some deeper SNP testing we know that we are from the Swedish branch of R-L238. Note that the current naming conventions are the umbrella group (so R) followed by the endmost SNP tested (L238). However my other Norwegian lines, my Wold and Skjold cousins are both the viking I haplogroups.

Jewish men may be interested in their haplogroup in case they are Cohanim (two lineages, one a subset of J1, the other of J2) or Levite (a subset of haplogroup R1a) – Click here for that wikipedia discussion. There are projects for both these groups at Family Tree DNA. An advantage of joining a project is that the administrator can often help you with your quest. On my Jewish side, my Steinhardts are T1 (Phoenician origin) but I have not yet found any male Engel, Langermann or Thannhauser descendants.  So many daughters!

However finding your Y haplogroup will not give you a surname. It may help disprove a patrilineal lineage if you have a different haplogroup from others with your surname. This often happens within a family when a man was adopted in or a daughter’s male child took her surname.


SNP tests are what are used to determine your haplogroup while STR tests give you more recent ancestry. Click here for more about the differences, although the above graphic may give you the idea.

To find your surname or others with your surname, you would take the STR 37, 67, or 111 marker test at Family Tree DNA and they also include your top level haplogroup with that test. I recommend the 67 marker test to start with. Then you can later choose to test more STR markers or test a package of SNPs suited to your haplogroup, as I did. Or you can go whole hog and get both the SNPs and STRs in one enormous package this father’s day, namely the Big Y-700.

There are also projects at Family Tree DNA for specific surnames. Click here for an example of a well done surname project

Warning, if you are from a population that did not have surnames until recently (for example Scandinavians and Ashkenazi jews) then an STR test will not find one for you. Also if no one from your Y lineage has tested, you will have no matches, a common complaint.

You can, however, use a Y STR marker test to prove a common male line ancestor between two possible cousins, perhaps even with the same surname. For example, my 4th grandfather was named Lars Monsen from the Bergen area of Norway. This is a very common name there, so we had not been able to figure out which family was his from the records. We developed a theory and did a Y test on a male line descendant of Lars’ possible grandfather. It was a match! Click here for that story.

Back when we did this, there was a common database for people who had tested their Y markers at different companies, like a GEDmatch for the Y. This was taken down due to GDPR concerns. I am pleased to announce that there is a now a new common database for Y and mtDNA in Beta test at https://www.mitoydna.org/ so please add your Y and mtDNA test results there.

Personally, I find the deep ancestry information contained in the Y haplogroups fascinating. I knew that the current Ancestry DNA test had a lot of Y data in it so I tried out the Morley Tool to see if it would predict my brother correctly. Sure enough it found that he was R-L238 which we know since he is my father’s son!

To try this yourself go to this page and follow the instructions. This should work for MyHeritage as well.
https://ytree.morleydna.com/extractFromAutosomal

Morley result for my brother

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3 thoughts on “Why Y?

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  1. Thanks so much for all the wonderful information Kitty! It is both fascinating and very helpful!
    -Cousin Kristin

  2. I’m new to genealogy and genetics so appreciate your blog that I learned about via Gedmatch. While reading it, I had the SBLS (School Bridge Lessons Series) Teacher Manual up on another tab. Confusion eventually became laughter. I have purchased for you a glass of wine each for both these hats you wear, duplicate bridge and genetics. Cheers!

    • LOL!!
      I am surprised that there are not more bridge players doing DNA. Similar mental skills. Our local club owner Wirt is getting more into it … And at least one other local player also.
      And thank you, I will toast you tonight as I drink one of those glasses 🙂

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