I’ve recently noted a trend among genealogists to discount unexpected (or unwanted?) DNA test results in order to make the results fit an existing hypothesis, instead of properly re-evaluating the hypothesis in light of the new DNA evidence. (This is NOT made in reference to any specific person, post, or question; it is rather something I’ve been mulling over for some time).
Let’s take third cousins as an example. According to Family Tree DNA’s FAQ, you will share detectable DNA with approximately 90% of your third cousins under FTDNA’s threshold. According to AncestryDNA’s help page (see “Should other family members get tested?”), you will share detectable DNA with 98% of your third cousins under AncestryDNA’s threshold. In other words, if you have 100 third cousins and they all get tested (how’d you do that?), you will share DNA with 98 of them.
As you might recall, a few weeks ago I sent out a call for information about the amount of DNA shared by people having a known genealogical relationship. I was hoping to get a better picture of the ranges of the amount of DNA shared by people in these relationships (through about the third cousin range). Although people like Tim Janzen have gathered this type of data and so kindly made it available for everyone, I felt like more data was needed.
What is the range of cMs shared by third cousins? What does the distribution within that range look like? Does the longest segment factor into that at all? If so, how?
These are the types of questions I wanted to examine. And to entice submissions, I offered a free Family Finder kit to one lucky person that submitted data prior to April 1, 2015.
[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.
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:
There will be lots more to come, including guidelines for Y-DNA and mtDNA testing and interpretation, as well as some guidance for citing DNA test results in reports, scholarship, and in general. Stay Tuned!
My grandmother Jane died in 1984 when I was just 8 years old. I have some really great memories of her, faded with time but still filled with emotion. Bath times, spending time with her in the summer, newspaper hats, chrysanthemums.
However, in addition to those memories, she gave me a very unique genetic heritage. She was from a region of the world with a high degree of admixture, and thus it is from her that I obtained my Native American mtDNA, my Native American, African American, and Spanish autosomal DNA. It is an incredibly rich and fascinating genetic legacy.
In an attempt to learn more about my grandmother’s genetic heritage, I’m using GEDmatch’s new Lazarus tool to try to recreate as much of her genome as possible. Join me on the journey, and learn about this new tool.
I 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.
If 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.
In 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.