Whose Y to Use? Paternal Ancestry for Ladies

gus.jpgOne of the most exciting parts of 23andMe’s Personal Genome Service™ is discovering your genetic ancestry. Suddenly your family tree has branches that reach back thousands of years into the prehistoric past.

At present, 23andMe customers can trace two branches of their genetic family tree – one that follows the all-female line on the maternal side (through mitochondrial DNA) and another the all-male line on the paternal side (through the Y chromosome).

Not all DNA is created equal, however: males have both mitochondrial DNA AND a Y chromosome, so they can trace both their maternal and paternal ancestry. Females, who have mitochondrial DNA but no Y chromosome, can trace only their maternal ancestry.

So how can females discover their paternal history? One solution is to ‘borrow’ the Y chromosome of her most immediate paternal ancestor – her father. A female can have her father send his own DNA sample to 23andMe, then examine his Y chromosome as a way of understanding his paternal ancestry and her own.

But what if a woman’s father can’t or won’t share his DNA? By sharing 23andMe accounts with the right male relative, a woman can still discover both her maternal and paternal ancestry.

So whose DNA can a female customer use, besides her father’s? It could be anyone who shares his Y chromosome – her brother, paternal uncle (father’s brother), or even paternal grandfather (father’s father). The chart below illustrates some of the possibilities in one woman’s family tree; male relatives who share her father’s Y chromosome are depicted in blue.

You may look at the chart and ask: Why not her son’s Y? After all, he’s a male relative, too. But even though a mother shares 50% of her genes with each of her children, only fathers pass Y chromosomes to their sons. So any examination of her son’s Y chromosome would yield not her father’s paternal history, but her husband’s.

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The woman whose family tree is shown here (“Me”) could determine her paternal ancestry using the Y chromosomes of males who are colored blue.






  • Scott23H

    Kitty,
    Her ancestry is a mix of both her father and her mother. Although we cannot easily identify what came from her father, there are ways to do that. If her mother were to test for instance she could then look at split view in the ancestry composition tool and see what ancestry came from her mother and what came from her father. The reason testing her son wouldn’t help is that the Y chromosome is passed on from father to son. That traces the paternal line. So her son didn’t get his Y from her father but from his father and his father’s father.

    • kitty

      Ok, but then what if the woman who has the father who was adopted but died also has no sisters and her mother is dead also ? Then she has only herself to take the test to find out what her father’s ancestry was, wouldn’t there still be a way since she would have half of what he was in her genetic pattern ?

      • Scott23H

        Hi Kitty,
        That will be much more difficult. It will take using other information she may have about either her mother or father. It may be that she can look at her DNA Relative matches. Some of those will be from her father’s side. Looking at how those matches cluster and the ancestry of those individuals may help. Again it will take some triangulating of information.

  • Maxwell98761

    I am another daughter interesting in finding more about her father’s genetic history under seemingly impossible circumstances. My question is how far down can you go in a male line that is parallel to my fathers line to get reliable dna paternal results? (my grandfather’s brother’s). My father and his brother only had daughters. I would only possibly have dna from my grandfather’s brother’s line of males. My father was born when my grandfather was 40 and my grandfather was one of the youngest of 12 and according to family history that I have, most of my grandfather’s brothers died when my own father was in his 30′s. To make matters worse, I was born when my father was almost 50. An available male cousin from my grandfather’s brother’s would probably be at least 3 (maybe 4) generations down the line. Is that too far removed to produce reliable and revelent results?

    • 23blog

      Maxwell,
      Just to be clear, you get DNA from both sides of your family, but if you are woman you need a male relative on your paternal side to be able to trace your paternal line.
      So that means you will get DNA relative matches from both sides of your family. The issue of identifying which side of the family a match comes from is harder however. You’d asked about whether you had your paternal grandfather’s son’s son tested whether that would be helpful. Yes that would give you your paternal haplogroup. As long as you can trace that directly through the male line to a common grandfather you could indeed use that to identify your paternal haplgroup. Here’s a link to more about linking a relatives paternal haplogroup. (https://customercare.23andme.com/hc/en-us/articles/202906940-Linking-a-relative-s-paternal-haplogroup)

      • Maxwell98761

        Thank you so much for your help!

  • caren

    Can I use my sister’s son to our fathers grandfather bloodline ?

    • Scott23H

      caren,
      The short answer is no that wouldn’t help you.

      For females, if a male relative such as your father, brother, paternal uncle or paternal male cousin were to be genotyped then you would be able to infer your own paternal haplogroup information from his. If your brother were to provide a sample, you would learn your maternal haplogroup as well as your paternal haplogroup.

      However, if your father or father’s brother were to provide a sample, you would learn your paternal haplogroup, but not your maternal haplogroup since he does not share your mother. If your biological father participates, you can link his paternal haplogroup to your profile so that it will appear on your own Paternal Line page.

      Haplogroups are one small part of your ancestry analysis. The 23andMe Personal Genome Service provides you with information from all branches of your family tree using your autosomal DNA.

  • Angela Sherman

    My question I hope isn’t too confusing. I understand about getting my paternal and maternal heritage. However I am wondering isn’t my mothers paternal line important to my ancestry too? Her being female also would mean that she didn’t get her fathers Y correct? Doesn’t that mean that I wouldn’t get to understand the heritage of my maternal grandfathers all the way down the line unless I had my grandfathers,or maternal uncle’s dna? My grandfather has passed so does that mean I would have to get my maternal uncle to give me that information?

    • 23blog

      Hi Angela,
      Your initial questions was a little confusing, so apologies for not responding sooner. The simple answer to your last question is no. You would still be able to see the ancestry contributions from both your maternal and paternal side. You will also be able to get DNA Relative matches from both sides of the family.

      The analysis of the 22 autosomes is the same for women and men and provides the same information and level of detail. For each pair of these chromosomes one comes from your mother and the other from your father: two copies of the same recipe with slightly different ingredients. The autosomes are what we use to determine your DNA Relatives, your Ancestry Composition results, your health and trait reports, and many other features. The great majority of our features are based on the autosomes.

      However, since men and women have different sex chromosomes, there are some small differences in the information they will receive. For example, men will only display a single X chromosome in features such as Ancestry Composition, while women will have two.
      Since women have two X chromosomes instead of an X and a Y, the 23andMe Personal Genome Service does not directly provide paternal haplogroup assignments for women. The paternal haplogroup is traced through the Y chromosome, which women do not inherit.

      • Angela Sherman

        Thank you for thoroughly answering my question. I again apologize for the confusion.

        • 23blog

          Glad to help Angela.

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