Small Matching Segments – Friend or Foe?

There has been a great deal of conversation in the genetic genealogy community over the past couple of weeks about the use of “small” segments of matching DNA. Typically, the term “small” refers to segments of 5 cM and smaller, although some people include segments of 7 cM or even 10 cM and smaller in the definition.

The question, essentially, is whether small segments of DNA can be used as genealogical evidence, and if so, how they can be used.

While it may seem at first that all shared segments of DNA could constitute genealogical evidence, unfortunately some small segments are IBS, creating “false positive” matches for reasons other than recent ancestry. These segments sometimes match because of lack of phasing, phasing errors, or a variety of other reasons. One thing, however, is clear: there is no debate in the genetic genealogy community that many small segments are false positive matches. There IS debate, however, regarding the rate of false positive matches, and what that means for the use of small segments as genealogical evidence.

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Bridging the Gap Between Traditional Genealogy and Genetic Genealogy at the NYG&B

logo.png  670×83I am incredibly honored to announce my election to the Board of Trustees of the New York Genealogical & Biographical Society! The NYG&B is the largest and oldest genealogical society in New York State, and the second oldest genealogical society in the nation. As a lifelong genealogist with New York roots dating back almost 250 years, joining the NYG&B is a dream come true for me.

Over the past decade, DNA has become a powerful tool for genealogical research. As a member of the NYG&B’s Board of Trustees, I hope to be able to help bridge the (ever-closing) gap between traditional genealogy and genetic genealogy, and help both members and non-members understand and incorporate DNA into their family histories.

The board represents an incredible group of people dedicated to helping people discovery their family histories, and I am so grateful to be able to join them. The full list is below.

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Goodbye False Positives! AncestryDNA Updates its Matching Algorithm

AncestryDNAYesterday, when I checked my AncestryDNA account I had 205 pages of matches, or 10,250 matches in the database. Today, thanks to Ancestry’s new matching algorithm, I have 57 pages of matches, or 2,850 matches in the database (a reduction of 72.2%!). I also have DNA Circles, groups of people who MIGHT share a common ancestor (some of whom share DNA with me).

A New Matching Algorithm

I wrote recently about the new algorithm (see “Finding Genetic Cousins – Separating Fact from Fiction“), as did Judy Russell (“When less is more“) and Roberta Estes (“DNA Day With Ancestry“). In essence, AncestryDNA is leveraging information about allele frequencies (“pile-ups”) in which small IBS segments of DNA shared by many, many people are not utilized for matching.

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Finally! GEDmatch Announces a Monetization Strategy (and a Way to Raise the Dead?)

GEDmatch   Tools for DNA and genealogy researchIf you’re serious about genetic genealogy, you’ve heard of GEDmatch. The third-party site is one of the few ways to compare testing results among the three testing companies. The site

However, since GEDmatch is run by two incredible volunteers (Curtis Rogers and John Olson) with full-time jobs, the site has experienced server issues and downtime. Many have lamented that there was no monetization plan in place, but gave donations in hope that it would help the site grow.

This week, GEDmatch announced a monetization strategy, namely advanced tools that are only available to Tier 1 members at a nominal cost of $10/month:

Basic GEDmatch programs remain free and we plan to keep them this way. Donations help cover the costs associated with running this site, and will provide you with the benefit of using the additional Tier 1 tools for a period of time equal to one month for every $10 donated. You may use the ‘Donate’ button below, for a one-time donation of any amount, or the ‘Join GEDmatch’ button to establish a recurring $10 per month amount.

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Transfer Raw Data to Family Tree DNA for $39 (Sneak Peek for FREE!)

At the Family Tree DNA 10th Annual International Conference, FTDNA announced that they were reducing the price of autosomal DNA transfers (from the AncestryDNA test or the V3 test from 23andMe) from $69 to $39. Additionally, you could upload your raw data for free and you would receive information about your 20 closest matches in the database. On top of that, if you convinced 4 others to transfer their raw data, you would receive a transfer for free!

It looks like the site went live tonight! The link is (

Here’s what you see at the intro screen:



Once you’ve uploaded, you’ll receive an email with a login and password. You’ll then receive a second email a short time later, after your results have been processed. In the meantime, you’ll see this:

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Finding Genetic Cousins – Separating Fact from Fiction

AncestryDNAShort Summary: Before the end of the year, AncestryDNA plans to update our match lists using a new algorithm that reduces the number of false positive matches. For the first time, matching DNA segments will be characterized as IBS (i.e., a false positive) based on something other than simply segment length.

AncestryDNA Day

Last Monday, October 6th, I and six other members of the genetic genealogy community attended a ‘Bloggers Day’ hosted by AncestryDNA at the San Francisco headquarters of Two other members of the group have already written about the event:

While at ‘Bloggers Day’ we discussed many issues including the Y-DNA and mtDNA databases originally scheduled for destruction, upcoming changes to AncestryDNA’s matching algorithm (much more below), and other upcoming changes to the AncestryDNA about which you will hopefully soon hear much more.

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Mapping Disease Genes to Our Ancestors – Mutation Mapped to 1620

ng3113-F1In 2008, I wrote about the case of Mr. and Mrs. George Fry, who are believed to have brought a particularly negative mutation with them to the New World from Europe in 1630 (“A Single Colon Cancer Gene Traced to 1630 – The Future of Genetic Genealogy?“). The mutation – in the APC gene – increases the likelihood of colon cancer, and has been found in many of the Fry’s living descendants.

In this months’s issue of Nature Genetics (see “Mutations in SGOL1 cause a novel cohesinopathy affecting heart and gut rhythm“), researchers using the BALSAC Population Database traced a founder mutation in SGOL1, which causes Chronic Atrial and Intestinal Dysrhythmia, termed CAID syndrome. So not only is it interesting that the same gene is involved in both heart rhythm and intestinal rhythm, but that the DNA has been mapped to this ancestral couple. The couple, whose names were not provided, were married in France in 1620 and arrived shortly thereafter in Nouvelle France.

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Ancient Genomes at GEDmatch

A great resource from Jay Chandrakumar at Genetic Genealogy Tools ( – SNPs extracted from sequenced ancient genomes and loaded into GEDmatch. Try out admixture tools with these GEDmatch profiles, but don’t expect many matches in One-to-Many!

Denisova – GEDMatch# F999903

Mezmaiskaya Neanderthal #1 – GEDMatch# F999909

Altai Neanderthal #2 – GEDMatch# F999902

Palaeo-Eskimo 2000 BC – GEDMatch# F999906

Clovis-Anzick – GEDMatch# F999912

For example, here’s the Palaeo-Eskimo 2000 BC (F999906) profile in MDLP K23b:

F999906 GEDmatch


AncestryDNA Continues to Refine the Reconstruction of Ancestral Genomes

GeneticGenealogyFutureStamp1I’ve written before about a poster presented by AncestryDNA at the American Society of Human Genetics 2013 annual meeting, entitled “Reconstruction of Ancestral Human Genomes from Genome-Wide DNA Matches.”  In the abstract, the group describes how they use sequencing information from hundreds of descendants of an 18th century couple to recreate portions of the genomes of that couple.

AncestryDNA’s 2014 ASHG Poster 

The AncestryDNA group has continued to refine the process of reconstructing the genomes of ancestral couples, and has a poster in this year’s American Society of Human Genetics annual meeting:

Title: Reconstruction of ancestral human haplotypes using genetic and genealogical data.

Author(s): J. M. Granka, R. E. Curtis, K. Noto, Y. Wang, J. K. Byrnes, M. J. Barber, N. M. Myres, C. A. Ball, K. G. Chahine

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A Response to the Genetic Testing Article in Vox

1This week in Vox, health reporter Julia Belluz (Twitter) wrote about genetic genealogy testing in “Genetic testing brings families together: And sometimes tears them apart.” The article focuses largely on testing company 23andMe, and presents the following thesis:

Direct-to-consumer DNA testing companies are revealing family secrets, many of which are emotionally damaging, without regard to those affected by the family secrets and without sufficient warning to the test-taker.

Unfortunately, rather than presenting a balanced view of the consequences of uncovering family secrets using DNA testing (and despite the title of the article), Belluz focuses only on examples of negative outcomes. The article is a perfect demonstration of “genetic exceptionalism,” the theory that genetic information is special and must therefore be treated differently from other types of information. Despite its many adherents, genetic exceptionalism is a theory without a logical underpinning.

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