Wednesday, November 20, 2013

Ancestry Composition, part two

More specific ancestral origins based on your DNA are available at 23andMe with the tool "Ancestry Composition."  If you have a short tree, seeing where in the world your DNA came from can help lead you to explore more areas in your research.  If you are adopted and know little or nothing of your origins, this feature will reveal your worldly makeup.

In an earlier post, I provided screenshots of Ancestry Composition.  My composition analysis is not different with the enhanced tool.  This is because I am mostly European.  The more specific geographical designations are found in the rest of the world.

These areas of the world have grown more specific in the Ancestry Composition feature
at 23andMe.  The percentage is zero because my DNA has no detectable ancestry from these areas.


In the time since my previous post on Ancestry Composition, my sister tested her DNA.  I can compare her composition to mine to see differences in inheritance.  Each sibling will differ in what they inherit and in what they pass on to the next generation.  The result is widening genetic differences among cousins with every generation until they may have little in common with one another as well as ancestors from long ago.


Above are ancestry compositions for my parents.  Each child will inherit a different amount of DNA from each area.  This is why Ancestry Composition is not a precise reflection of your ancestral origins.



My Ancestry Composition differs a little from my sister's.  Future generations will receive different combinations of the ancestries.  Some ancestral areas may completely disappear from the DNA of future generations.  This is why Ancestry Composition will not reflect all the areas of the world where your ancestors were from.  Asian ancestry was not detected in our parents, perhaps because the amount was just under a threshold.  We may have had Asian or Native American ancestors.  It is possible that all ancestors of the last several generations were European and diluted the Asian DNA to reach an almost undetectable amount in us, the current generation.

Envision your 128 great-great-great-great-great grandparents.  If one was Asian and the other 127 were European, you likely would have little to no detectable ancestry from Asia.