DNA Comparisons

23andMe/Autosomal DNA testing of family members

Below are actual graphs of the comparisons between different members of my family who have tested their autosomal DNA at 23andMe.  The true relationship is documented.

I want you to notice that the most DNA is shared between a parent and a child, 50%, as well as full siblings- about 50%.  As the relationship widens, the amount of identical DNA plummets to almost undetectable amounts beyond a third cousin relationship.

You can use these graphs to help figure out relationships between close family members of unknown origins.  If you have specific questions about a particular graph, such as the path of inheritance or ethnicity of the involved individuals, please contact me.

Parents and children


Aunts and Uncles

First cousins

First cousins, once removed

First cousins, twice removed

Second cousins

Second cousins, once removed

Third cousins

Third cousins, once removed

Fourth Cousins

Fourth Cousins, once removed


  1. 23 and me is reporting a match with a first and second cousin. Someone mentioned that the first cousin and I could also be half niece/half aunt. Is there a way to read any of the 23&me reports to narrow this down? In speaking about our family history we think we might be related via her paternal grandmother who we blindly theorize might have given birth to my mother (or father) out of wedlock and given him or up. If its niece/nephew I've got to really rethink what kind of clue she provides to my trying to figure out my birth parents.

    1. That is a good match for unknown parentage.
      First cousins and half aunt/niece will share about 12.5% DNA.
      Aunts or uncles and nieces will TEND to share longer segments of DNA because they are missing one generation of recombination compared to first cousins. However, women's DNA tends to recombine more than men's.
      Upload to GedMatch if you have not done so.
      Look at the X chromosome. If you match on this chromosome, only certain paths of relatedness are possible.
      Look at the predicted mt-dna haplogroup. This is another specific path.