GUEST POST – What a Difference a Phase Makes

The following is a guest post by Ann Turner, founder of the of the GENEALOGY-DNA mailing list at RootsWeb and co-author (with Megan Smolenyak) of “Trace Your Roots with DNA: Using Genetic Tests to Explore Your Family Tree.” Thank you Ann for this terrific post!

Genetic genealogists use autosomal DNA testing to locate people who share some DNA, enough to point to a relationship in a genealogical time frame. We’re not impressed by accidental matches that occur simply because all humans share 99.9% of their DNA. We want to be confident that the shared DNA segment is Identical by Descent (IBD) from a particular common ancestor, one who lived some number of generations in the past.

Two practical difficulties stand in the way of definitive confirmation. One is that our pedigrees are not complete, and we cannot test every link in the chain to prove that the segment traveled down the pathway we’ve identified through the paper trail. Indeed, as more data accumulates we frequently discover that a match we attributed to one ancestor must have come through an entirely different line.

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How Would You Like to (Finally!) Understand Autosomal DNA?

Genetic-Tree-Showing-Ethnicity-Loss[Read on to learn how you could win THREE hours of FREE consultation and research from me for registering in this course before March 21st!]

For the next two Saturdays, March 21st and 28th, I will be spending some quality time with genetic genealogists! My new course entitled “(Finally!) Understanding Autosomal DNA” is a four session course designed to educate genealogists on all the ins and outs of autosomal DNA.

The course is being offered through the wonderful new Virtual Institute of Genealogical Research. The Virtual Institute offers courses on a wide variety of genealogical subjects, providing vigorous year-round education for the genealogical community using a virtual platform.

The four courses will provide attendees with the fundamentals of autosomal DNA, third-party tools, and triangulation. Here is the course schedule (all times U.S. Eastern):

21 March 2015

  • 11:00am – “Introduction to Autosomal DNA”: Learn the fundamentals of autosomal DNA and compare company offerings.
  • 1:00pm – “Using Third-Party Tools”: Free tools offer powerful additional analysis of autosomal DNA test results.

28 March 2015

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Collecting Sharing Information for Known Relationships

EDIT (3/31/2015) – Beginning on April 1, 2015, I will no longer be able to accept submissions other than through the portal. My sincerest apologies, and I so greatly appreciate the files that have been submitted this way, but I have been inundated and won’t be able to take the extra time to process any non-portal submissions made after April 1, 2015. Thank you!

I need your help! I’m trying to gather data about the ranges of DNA shared by known relatives. How much DNA do you share with your sister? your brother? your second cousin? While it is possible to predict approximately how much DNA you share with a close relative, the actual numbers vary more than you might think.

If you’re interested in participating in this project, I’m looking for two numbers for the known relationship: (1) the total amount of shared DNA in cMs; and (2) the largest shared block in cMs. At Family Tree DNA, for example, you can find the numbers here:

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