Tuesday, May 14, 2013

Tuesday’s Tip – Understanding Genetic Genealogy



I better understand genetic testing thanks to an excellent presentation last Saturday on DNA by Shannon Combs Bennett.  If you read Shannon’s recent blog you will note she confesses she was nervous, but from an audience point of view Shannon was nothing less than a experienced, polished, professional sharing her scientific knowledge at a level that novices could easily understand.

The room was packed indicating DNA/Genetic Genealogy is an area of great interest.  Thanks to Shannon, we all went home with a much better understanding of the tests available, what each test accomplishes, the unique qualities of the companies that do testing, and genetic related blogs and books available. 

She emphasized that DNA testing is only a tool; it will not give you definitive answers.  You should couple your DNA test results with your paper genealogy research.

A timeline of genetic history and useful terminology were then provided. I am thankful she provided us with eight pages of backup for her talk!

There are three types of testing:

Autosomal DNA is open to everyone. This test will give you ancestral results back to seven generations.  Since each generation loses some of the genetic material from past generations, this test is best combined with your paper research.

Y-DNA is the sex chromosome and is passed from father to son only. You can use this to find your haplotype that may give you origins of ancient male ancestors.  When viewing results, there needs to be as few mutations as possible.  Shannon had excellent examples of these tests using her own family’s results. These examples provided the ah-ha moment of understanding.  She also explained there is a surname study for men that you may want to check out.

mtDNA is a test to trace maternal ancestors.  Since mutations in mitochondria are relatively rare, this test is used for deep ancestry research.  Researchers believe that everyone is related to “mitochondrial Eve.”

There are four companies doing genetic testing:

FTDNA – Family Tree DNA offers complete genetic testing for genealogy, and we believe at this time they keep the results.

23and Me – This California company does testing for medical history purposes.

AncestryDNA – Primarily autosomal testing, they allow uploads of information from other companies.  Their policies are in flux, and as of now they destroy the information soon after.  It is a good idea to thoroughly check out any company you are considering for their particular policies.

National Geographic Genographic Project – This multi-year anthropologic genetic study is doing only Y-DNA at this time.  Again, projects change so it is your responsibility to do due diligence research.

To assist with your test decision-making Shannon recommended utilizing Tim Janzen’s Autosomal DNA Test Comparison Chart.

This blog lightly skims over Shannon’s presentation.  For more information also check out the In-Depth Genealogy website ( http://www.theindepthgenealogist.com/).   Shannon writes the tech section of this online genealogy magazine. There are also articles explaining DNA testing.


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