The Shared cM Project

Announcing “The Family Tree Guide to DNA Testing and Genetic Genealogy”

s7981_new01I am so happy to officially announce “The Family Tree Guide to DNA Testing and Genetic Genealogy,” my effort to help people understand DNA and genetic genealogy. The book, published by Family Tree Books, is 240 pages long and covers every aspect of DNA testing for ancestry research:

  • Part One: Getting Started – Genetic Genealogy Basics; Common Misconceptions; and Ethics and Genetic Genealogy
  • Part Two: Selecting a Test – Mitochondrial-DNA (mtDNA) Testing; Y-Chromosomal (Y-DNA) Testing; Autosomal-DNA (atDNA) Testing; and X-Chromosomal (X-DNA) Testing
  • Part Three: Analyzing and Applying Test Results – Third-Party Autosomal-DNA Tools; Ethnicity Estimates; Analyzing Complex Questions with DNA; Genetic Testing for Adoptees; and The Future of Genetic Genealogy
  • Appendices – Comparison Guides; Research Forms; and More Resources

For a preview of the book, you can visit the Amazon page or Google Books.

As you’ll see, the book is full of color images that help explain all aspects of DNA and genetic genealogy, like the following (only a portion of each are shown):



Here are a few reviews of The Guide:

You can also hear me talk about The Guide on Episode #8 of The Genealogy Connection with Drew Smith.

The book is available for purchase at the following:

And, if you’ve purchased and read The Guide, please consider leaving a review at Amazon!

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Second Cousins (Or Closer) That Don’t Share DNA?

Caution should always be taken before pursuing an answer to a genealogical question. Ask yourself (or your relative) before diving into the research whether you really want to know the answer, and whether you think you are prepared for it. Just because you as a genealogist may be prepared for the result does not mean everyone in your family will be.

This is as true with DNA evidence as it is with any other type of genealogical evidence. Just as a census record or birth certificate can reveal a family secret, so can the results of a DNA test. The Genetic Genealogy Standards, for example, make clear that unexpected results can occur:

12. Unexpected Results. Genealogists understand that DNA test results, like traditional genealogical records, can reveal unexpected information about the tester and his or her immediate family, ancestors, and/or descendants. For example, both DNA test results and traditional genealogical records can reveal misattributed parentage, adoption, health information, previously unknown family members, and errors in well-researched family trees, among other unexpected outcomes.

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Genetic Genealogy and Native American DNA

[EDIT (7/6/2016): Razib Khan discusses the same issue here.]

I despise all politics. I suppose someone has to do it, but I always do my best to avoid discussing it either in person or online. I consider it to be a huge success when people don’t know my political leanings (is “away from all politics” a political leaning?).

Currently, however, there is a political figure who potentially has asserted that he or she might have distant Native American ancestors (specifically, Cherokee ancestors). For no real reason other than politics, some have disputed the claim, and the media is actually writing stories about it. Trust me, this whole ‘debate’ surrounding one person’s ancestry is so unbelievably unimportant that you don’t want to waste your time to look it up.

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Update to the Shared cM Project

[EDIT: PDF edited on 31 July 2016 to correct the averages for 1C and 1C1R (hat tip to Andrew Millard, thank you!)]

The Shared cM Project is a collaborative data collection and analysis project created to understand the ranges of shared centimorgans associated with various known relationships. As of June 2016, total shared cM data for more than 10,000 known relationships has been provided.

This is the first update to the original data, released in May 2015. In this update there are more than 4,000 new entries. Additionally, the data for each relationship has been analyzed statistically to remove extreme outliers and produce a histogram to show the distribution.

For more information see The Shared cM Project page, and “Autosomal DNA Statistics” page at the ISOGG Wiki. HERE is the link to provide your data for future updates.

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Charging for (Genetic) Genealogy Services

wordcloudIn our culture and economy, we place a value on the goods and services that we create or offer. Since others may not have the time or ability to create those goods or services themselves, we sell what we create to others in order to earn money. As we improve upon those goods and services, it becomes increasingly hard for others to replicate them, and thus the value increases. Similarly, as the demand for those goods and services increases, the value increases.

Unfortunately, the services offered by genealogists, including genetic genealogists, are severely undervalued in our culture. One of the most common explanations is that genealogy is a hobby and therefore subscriptions and research services are an unnecessary expense, and/or that people only use “disposable income” for genealogy. (Don’t say that outloud at a genealogy conference!).

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A Triangulation Intervention

Autosomal DNA is challenging. Although the results of atDNA testing contains vastly more information than either Y-DNA or mtDNA, it is significantly harder to utilize and understand. To wring as much information as possible out of atDNA test, genetic genealogists use every tool available.

One of those tools is triangulation. Although the topic of much debate recently, and subject to several important considerations and limitations, most genealogists agree that triangulation is a valuable tool for working with segments (especially among close relatives).

Unfortunately, there is a lot of misunderstanding when it comes to what is – and what is not – triangulation.

Let’s take a quick look at what triangulation means with regard to atDNA, and why it matters.

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Family Tree DNA Updates Matching Thresholds

Family Tree DNA will be updating its matching thresholds in the very near future (QC is currently being run). Here’s a flowchart of the modified matching algorithm:


From FTDNA’s announcement (modified to indicate that the changes are coming very soon):

You asked for it – we listened!

For several years the genetic genealogy community has asked for adjustments to the matching thresholds in the Family Finder autosomal test.

Currently, the current matching thresholds – the minimum amount of shared DNA required for two people to show as a match are:

– Minimum longest block of at least 7.69 cM for 99% of testers, 5.5 cM for the other one percent

– Minimum 20 total shared centiMorgans

Some people believed those thresholds to be too restrictive, and through the years requested changes that would loosen those restrictions.

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Connections to the Past

As genealogists, we often have the privilege to connect with relatives who have memories that stretch back much further than our own. Sometimes these connections are long-lasting, and sometimes they are very brief. But every one of these connections enrich our understanding of the past, and help keep alive ancestors that live on only in their memories.


A smiling Millie with her parents Hamilton and Grace (Widrig) Colwell, and her baby.

On June 1, 2002, I had the privilege to meet Mildred “Millie” Leet, who lived 3 hours away in Corning, New York. I’d briefly corresponded by mail with Millie about our shared ancestors, the Colwell Family of Ellisburg, New York. She was the great-grandchild of the immigrant couple Hamilton and Susanna (Stein/Steen) Caldwell/Colwell, my ancestors as well, and she was born just 20 years or so after their death.

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Announcing “Genetic Genealogy in Practice” – A New Book Providing Genealogists with the Skills to Understand and Apply DNA

GGPEDIT: See Debbie’s post here: “New Book Coming Soon: Genetic Genealogy in Practice” with lots more detail!

May 3, 2016 – Genetic genealogy educators and bloggers Blaine T. Bettinger, Ph.D., JD, and Debbie Parker Wayne, CG, CGL, announce Genetic Genealogy in Practice, the newest book in the National Genealogical Society’s Special Topic Series. GGP will be available for purchase in mid-summer 2016.

Genetic Genealogy in Practice is directed to genealogists of all levels, from beginner to intermediate to advanced. For the very first time, GGP offers hands-on exercises in areas of Y-DNA, mtDNA, X-DNA, atDNA, the Genealogical Proof Standard, ethics, and more. Genealogists can test their understanding and expertise in each of these subject areas via 75+ hands-on exercises, and will receive immediate feedback from an answer key that provides detailed explanations for every exercise.

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AncestryDNA Plans Update to Matching Algorithm

AncestryDNAAncestryDNA is making several changes to its matching algorithm in the next week or two (an exact time is not yet available). You may recall an announcement that was made earlier this month entitled “New Advances in DNA Science Coming Your Way” (pdf) in which they stated the following:

“These advancements are expected to deliver more-precise predictions of whom you are related to, and how closely, among the million-plus others in the AncestryDNA database.”

There were no specifics in the announcement, however. Last night, AncestryDNA provided additional information about the changes that we will be seeing in our match lists in the next week or two.

Before I launch into the specifics, here is a very high-level summary, based on the information we were provided:

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