23andMe Trouble – Step-by-Step Instructions to Preserve Your Data and Matches

I don’t know what the future holds for 23andMe, but the financial floodwaters are rising. I’ve been torn about whether I should risk alarming people, perhaps unnecessarily, by writing about this, and if so, exactly what to say.

I’ve decided that the responsible action is to share my concerns with you and suggest that you act proactively – just in case.

Contrary to linking within this article which is what I normally do, I’m placing a list of relevant articles about what’s happening at 23andMe at the end for your reference. There are quite a few. I’ve located reputable articles without paywalls. There are even more publications today.

What’s Going On?

If you’re following the saga of 23andMe, you’ll know that they have been in financial trouble for some time, worsened by their data breach in October 2023. Not only was customer information accessed and downloaded, but 23andMe reacted extremely slowly, which made the situation worse. Lawsuits followed. I’ve written about the deteriorating situation several times.

Their financial situation has continued its decline ever since.

Recent developments, including the inability of Anne Wojcicki to raise funding to take the company private again, the $30 million data breach settlement this week, a further drop in their stock price, and just yesterday, the resignation of the board of directors in its entirety (except for Wojcicki), makes their future increasingly uncertain if not outright bleak.

Concerns

I am very concerned about the future of 23andMe. Never having experienced anything like this in our industry, I have no prediction about exactly what will happen, or when. That’s unknowable. I do know that I’m quite worried as are other professionals in this field.

I am strongly considering deleting my 23andme accounts. My personal hesitation is that I author this blog and I can’t write about 23andMe if I don’t have an account there.

Were it not for that, I would strongly consider deleting my account after recording my matches and downloading my data. 23andMe has ceased to be useful for me and has increasingly become a liability.

Please do NOT panic and run over there and delete your account without thoughtful consideration and taking these preservation measures first. Truly, I will tell you if I think you need to act on something immediately, as I have in the past.

I am NOT specifically recommending deleting your account. Everyone’s circumstances and goals are different.

For example, if you’re an adoptee fishing in all the ponds, you may want to wait. If your focus is health, you’re probably not reading this article, but that might be justification for people to wait. Or, if you’re a genealogist who wants as many matches as possible, you may want to wait and see how things shake out.

Regardless, the following recommendations ARE for everyone. Being prepared is better than being surprised.

Recommendations

Whether you choose to delete your account at 23andMe in the near future, wait, or maybe never, I have the following recommendations, just in case.

  1. Download your raw DNA data file.
  2. Preserve your matches in some fashion.
  3. Save your ethnicity segments file.

Here are step-by-step instructions for each item, plus several tips and hints.

Download Your Raw DNA File

Download your raw DNA file so that you can upload it elsewhere if you wish.

To download your raw DNA file, click on Resources, then “Browse Data.”

Select “Download” at the top of the next page where you will be prompted for your birth date.

You will then see a full page of “Important Warnings to Consider.”

Scroll to the bottom

Check the “I understand” box and then click on “Submit Request.”

You will receive an email when your file is ready to be downloaded.

If your email is not current, you will need to call or contact 23andMe support for assistance.

You can upload your 23andMe DNA file to MyHeritage, here, to GEDmatch, and to FamilyTreeDNA again soon. I’ve written instructions for uploading and downloading data to/from each vendor in the article DNA File Upload-Download and Transfer Instructions to and from DNA Testing Companies, here.

Preserve Your 23andMe Matches

Next, review and preserve your matches shown under DNA Relatives. You may want to use screenshots or create a spreadsheet, which is my recommendation. You’ll be able to retain and preserve a LOT more information using a spreadsheet, including how your matches are related to each other.

The good news, or bad news, depending on your perspective, is that unless you have paid for a subscription, you’ll only have 1500 matches to deal with. With a subscription, you’ll have up to about 5,000.

Match Information Spreadsheet

I suggest working with your closest matches first.

You’ll find your matches under “Ancestry,” then “DNA Relatives.” Matches are listed in the closest match order.

For each match you can view information, including:

  • Birth year and location
  • Your predicted relationship
  • If they are in the genetic tree that 23andMe has created for you
  • Their ancestors’ birthplaces, if they have provided that information.
  • Their family surnames
  • An important link to their family tree if they have provided that link
  • Their ethnicity which may be important if you share a common ethnicity that suggests or precludes lineages
  • High level Y-DNA and mitochondrial DNA haplogroups
  • Relatives in Common which are shared matches – and how much DNA your two matches share with each other
  • Any notes you’ve made

Other features previously available at 23andMe were discontinued after the breach.

If you downloaded your matches file before the October 2023 breach, you’re in luck because you can simply update that file with your new matches except for segment information. That’s what I’m doing. Your download file will be a CSV file styled “roberta_estes_relatives_download” where your name replaces mine.

If you didn’t download your matches before the breach, you can’t today, as that’s one of the features they removed after the breach.

Recording your matches’ information is the first step, but there’s an important second step too that will help you piece all of this information together.

Relatives in Common Relationship Grid

I strongly suggest creating a relationship grid detailing who matches whom for your shared matches. Yes, I know that’s a LOT of work, but it may well be worth it to wring every ounce out of your DNA matches. Plus, you can then keep it current as new matches arrive. Right now, I’ve set a goal for myself to complete 100 per day. That’s do able.

The “Relatives in Common” feature is extremely useful and facilitates constructing your tree and fitting your matches into their relative places in your tree. Relatives in Common tells you not only how much DNA you share with your matches but also their estimated relationship to each other and how much DNA they share.

To begin the process, you really only need to be able to identify “someone” and then chain people together based on shared matches and estimated relationships. I’ll show you.

To find Relatives in Common information and how much DNA they share with each other, click on a specific match, preferably one that you know, under DNA Relatives, then scroll down to “Find Relatives in Common.”

Here’s the list of matches shared between DH and me.

Here’s the beginning of the relationship spreadsheet I created.

This example shows the amount of DNA I share with my matches in the left column, then how much they share with each other. I’ve color-coded the results. Blue is my father’s paternal line. His mother’s line is not represented in these matches. Purple is my mother’s maternal line, and apricot is her paternal line.

DH is estimated by 23andMe to be my second cousin and shares 7.13% of my paternal DNA across 17 segments. DH also shares DNA with James, George, Daniel, RA, and Joyce.

You can see how much DNA any match shares with me, as well as with any other match, which I’ve entered into the chart.

Unfortunately, only one person, Patricia, has included a link to a tree, but our common ancestor was shown there. In two other cases, surnames provided information, as did previous communications. I can fit almost every one of these people into my tree, at least tentatively, using this information. Sometimes I match them at other vendors too, providing additional information.

If you used Genetic Affairs to cluster your 23andMe matches before the breach, you may already have at least part of your match and shared match information. I save everything to my computer, and I hope you did too.

I happen to know how two of these people are related to me, so I can begin my “shared tree” there, adding other people as I figure out their shared relationships. For example, if a match is my second cousin and also a second cousin to another match, chances are really good that we all share great-grandparents. Remember that 23andMe has taken a stab at genetic tree construction on their genetically created (now nearly unreadable) Family Tree, found under “Family and Friends.”

This tree may or may not help you.

Please note – if you wish to message any of your matches, you need to do that through the 23andMe internal platform, so don’t wait, do it now by clicking on your match, then “Message.”

Download Your Ethnicity Results and Segments

Download your ethnicity results and segment information so that you can use your segment location information to compare to matches from other companies that provide matching segment information.

Your ethnicity information is available under Ancestry, then Ancestry Composition, then Select Scientific Details.

Scroll all the way to the bottom – which is a LONG way.

Select the confidence level and then click on Download Raw Data.” I use 50%, but you can download each one if you want.

The resulting file holds the locations on your chromosomes of your various estimated ethnicities. You can upload that file to DNAPainter to correlate with your matches from any testing company, and with ancestors whose DNA you’ve identified.

I wrote about that, here, and have discussed how to “walk ethnicity segments back in time” using DNAPainter in several presentations. This technique is how I identified my Native American ancestor on my mother’s side, which was then confirmed by mitochondrial DNA testing on an appropriately descended individual.

Prognosis

If 23andMe remains viable, you’ll be ahead of the game. You’ll have preserved your information and may have identified some new matches and their ancestors.

However, if 23andMe doesn’t survive or is sold, you’ll have protected your investment and won’t be caught by surprise.

If you’re thinking about deleting your account, take the steps set forth above, first. The reason I’m providing this information now is so that, in case something happens, you have time to complete these tasks to protect your important information and matches.

If you choose to delete your 23andMe account, you’ll have preserved as much of your investment as possible. Remember, think before deleting because once you’ve deleted your account, you can’t undo it without testing again. This is especially important if you’re managing the DNA of someone who is now deceased. In that case, delete is irrecoverable.

Let’s just hope this all blows over, and you’ll have benefitted by finding new genealogy information.

Recent News Articles

https://www.cnbc.com/2024/07/31/23andme-ceo-anne-wojcicki-files-proposal-to-take-company-private-.html

https://investors.23andme.com/news-releases/news-release-details/23andme-special-committee-responds-ceos-take-private-proposal

https://www.reuters.com/technology/cybersecurity/23andme-settles-data-breach-lawsuit-30-million-2024-09-13/

https://www.cnbc.com/2024/09/17/23andme-independent-directors-resign-from-board-read-the-ceo-memo.html

https://www.washingtonpost.com/business/2024/09/18/23andme-board-turmoil-dna-test/

https://www.axios.com/2024/09/18/23andme-resignations-anne-wojcicki

https://investors.23andme.com/news-releases/news-release-details/independent-directors-23andme-resign-board

https://investors.23andme.com/node/9531/pdf

My Articles

https://dna-explained.com/2023/08/17/23andme-and-glaksosmithkline-partnership-ends-sparking-additional-layoffs/

https://dna-explained.com/2023/10/07/23andme-user-accounts-exposed-change-your-password-now/

https://dna-explained.com/2023/10/24/the-23andme-data-exposure-new-info-considerations-and-a-pause-strategy/

https://dna-explained.com/2023/10/29/23andme-dna-relatives-connections-event-history-report-and-other-security-tools/

https://dna-explained.com/2023/12/07/23andme-concludes-their-investigation-6-9-million-customers-data-exposed/

Six Ways to Figure Out How We’re Related

In my latest Webinar, Six Ways to Figure Out How We’re Related, I discuss the various tools from Ancestry, FamilyTreeDNA, MyHeritage, and 23andMe – plus clusters from Genetic Affairs and the amazing DNAPainter.

This webinar lives in the Legacy Family Tree Webinar library, but as part of the “webtember” lineup, you can view it for free through the end of September.

It’s always exciting to discover a new match at one of the DNA testing companies, which, of course, begs the question of how you’re related.

So, what are the six ways to figure out how you’re related, and how do you use them?

Come along for a step-by-step guide!

Shared Matches

We begin with how each vendor handles shared matches, what that feature is called, where to find the information, and how to interpret what they are telling you.

23andMe goes a step further and creates a genetic tree, of sorts, although that functionality has changed since their breach last October.

Bucketing and Sides

Two vendors go a step further and provide unique tools to divide your matches maternally and paternally.

FamilyTreeDNA buckets your matches maternally and paternally (or both) based on matches you link to their profile cards in your tree. FamilyTreeDNA then uses your linked matches to triangulate with other matches and assign your matches accordingly, providing a maternal and paternal match list. Bucketing, also known as Family Matching, is one of my favorite tools.

Note that linking matches at FamilyTreeDNA requires that you have transferred your tree to MyHeritage. I wrote about that and provided instructions here and here, and produced a complimentary webinar, too.

Ancestry also divides your matches by parent, but they use a different technique based on their Sideview technology and either ethnicity or shared matches.

Surnames and Locations

Surnames and locations, either separately or together, provide HUGE hints!

MyHeritage provides a nice summary for each of your matches that includes ancestral surnames, a map of locations in common, and “Smart Matches” which shows you people in common in both of your trees. There are several ways to use these tools.

FamilyTreeDNA also provides a list of surnames. You can view either the surnames in common with a match, or all of their ancestral surnames, with locations if provided. The tester enters these surnames, and we review how to complete that step.

Ancestry also provides shared surnames, with clickable links to the number of people in your matches tree with that surname, plus common locations.

X-DNA

X-DNA is probably the most underutilized DNA matching tool. While each of the vendors actually test the X chromosome, only one, FamilyTreeDNA, provides X-matching. You can obtain X-matching results by uploading your DNA file to FamilyTreeDNA. I’ve provided upload/download instructions for all companies, here.

X-DNA has a very unique inheritance pattern because males only inherit an X chromosome from their mother which limits the number of potential common ancestors for any two testers. In other words, X-DNA matching does half your work for you!

Clustering Technology – AutoClusters, the Matrix and DNAPainter

In the past few years, match clustering has become a very useful tool. Clustering shows which of your matches match you and each other.

Genetic Affairs offers several flavors of these clusters, and both MyHeritage and GEDmatch have incorporated Genetic Affairs clusters into their product offerings.

If you haven’t used AutoClusters yet, by all means, try them out.

FamilyTreeDNA offers the Matrix, a slightly different version of clustering. You can select 10 people from your match list to see if they also match each other. Shared matches don’t automatically mean triangulation between you and those two people, or even that all three people descend from the same line. However, if the people are bucketed to your same side (parent) and they share common segments with you in the chromosome browser, they triangulate.

You’ll want to paint those matches to DNAPainter to determine which ancestor you share, especially if they haven’t provided a tree.

DNAPainter provides your chromosomes as the “canvas” upon which to paint your matches in order to correlate segments with ancestors and identify common ancestral lines with mystery matches.

Three vendors, FamilyTreeDNA, MyHeritage, and GEDmatch provide segment information with matches for you to paint. I illustrate how I walk segments back in time, identifying our most distant common ancestor possible.

Theories of Family Relativity and ThruLines

Both MyHeritage and Ancestry provide a combination of DNA matching and tree triangulation, where they search the trees of your DNA matches to find common ancestors with you – although their implementation is different.

MyHeritage’s Theories of Family Relativity provides varying theories about common ancestors for you and a specific match using both trees and historical documents. You can review the various pathways and confirm or reject theories. I love this tool.

Ancestry’s Thrulines functions a bit differently, showing you all of your matches that descend from a common ancestor in all your matches’ trees. Sometimes, the trees are incorrect, but Theories of Family Relativity and ThruLines should still be used as hints.

I showed how ThruLines helped me discover what happened to one of my ancestor’s grandchildren who was lost to the family at his mother’s death – and to all of us since. Not anymore.

Bonus – Y-DNA and Mitochondrial DNA at FamilyTreeDNA

Only FamilyTreeDNA offers both Y-DNA and Mitochondrial DNA testing and matching. All of the tools above pertain to autosomal DNA testing, which is named Family Finder at FamilyTreeDNA. Illustrated by the green arrow below, autosomal DNA testing measures and compares the DNA you inherited from each ancestral line, but that’s not the only game in town.

Y-DNA, in blue, for males, tracks the direct paternal line, which is the surname line in Western cultures. Mitochondrial DNA, in red, is passed from mothers to all of their children. Therefore, everyone can test, revealing matches and information about their mother’s direct matrilineal lineage.

Y-DNA testing includes the amazing Discover tool with a baker’s dozen different reports, including ancient DNA. Mitochondrial DNA will soon have its own MitoDiscover after the rollout of the new Mitotree.

Both tests include “Matches Maps” to help you determine how you are related to your matches, as well as where your ancestors came from before the advent of surnames.

The Advanced Matching feature allows you to select multiple tests to see if your matches match you on combined types of tests.

Tune In

Now that you know what we cover in the webinar, please tune in to see how to use these awesome tools. Be sure to fish in all four “ponds” plus GEDmatch, where you may find people who didn’t test at a company that provides a chromosome browser or matching segment information.

Tools provided by the DNA testing vendors facilitate multiple ways to determine how we match and which ancestor(s) we have in common.

You can watch the webinar, here.

Additionally, subscribers to Legacy Family Tree Webinars have access to the 25-page syllabus with even more information!

A Legacy Family Tree Webinar subscription normally costs $49.95 per year, but through the end of September, there’s a coupon code good for 20% off. Just click here, then enter webtember24 at the checkout.

Enjoy!

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I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase your price but helps me keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

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DNA Academy Webinar Series Released

Great news! Legacy Family Tree Webinars has just released DNA Academy.

DNA Academy is a three-part series designed to introduce the basics of DNA for genetic genealogy and how Y-DNA, X-DNA, mitochondrial and autosomal DNA can be utilized. Each of these different types of DNA serves a different function for genealogists – and reveals different matches and hints for genealogy.

  1. DNA Academy Part 1 introduces genetic genealogy basics, then, Ancestry’s DNA tools – including their new pricing structure for DNA features. Click here to view.
  2. DNA Academy Part 2 covers FamilyTreeDNA’s products. Click here to view the webinar, which includes:
    1. Y-DNA for males which tracks the direct paternal line
    2. Mitochondrial DNA for everyone which tracks your direct maternal line – your mother’s mother’s mother’s lineage
    3. Autosomal DNA which includes matches from all of your ancestral lines and along with X-DNA matching, which has a very distinctive inheritance path.
  3. DNA Academy Part 3 includes MyHeritage, 23andMe, and third-party tools such as DNAPainter and Genetic Affairs. Click here to view.

Legacy Family Tree Webinars has graciously made Part 2, the FamilyTreeDNA class, free through August 22nd for everyone – so be sure to watch now.

After August 22nd, Part 2 will join Part 1 and Part 3 in the webinar library for subscribers with more than 2240 webinars for $49.95 per year.

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I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase your price but helps me keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

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Ancestry’s ProTools – See How Much DNA Your Matches Share and Their Relationship to Each Other

Ancestry reports that a ProTools subscription is available to all US users now – and with it, access to additional DNA match information. Oh, happy day!!

ProTools is Ancestry’s new offering that provides DNA testers with:

  • How you and any selected DNA match are BOTH related to your mutually shared matches
  • How much DNA a selected match and any shared match share with each other

Please note that ProTools does NOT include a chromosome browser, and the location of your matching DNA is NOT revealed. Shared matches and shared DNA does NOT equate to triangulation because the matches may be on different segments or due to different ancestors altogether.

Shared matching means that you match person 1 and person 2, and that person 1 and person 2 also match each other. It does not mean that you match on the same segment or because of the same ancestor.

Even if you don’t have or want ProTools, you need to read this article so you understand what your matches who subscribe to ProTools can now see about you and your relatives, especially your close relatives.

How Do I Find ProTools?

To determine if ProTools is available to you, click on any match in your DNA match list. You’ll see normal match information, displayed below.

At the bottom, you’ll see a banner inviting you to upgrade to ProTools.

ProTools provides multiple features for $10 per month ($120 per year), in addition to your regular or AncestryDNA Plus subscription.

ProTools includes other features as well, which I’m not reviewing today in order to focus specifically on the new enhanced Shared Matches feature.

I subscribed to ProTools and immediately had access to the new features.

Now, I see the “Pro” label beside Shared Matches.

Click on Shared Matches.

ProToolsShared Matches

By clicking on Shared Matches, I can now see how my match, ER, and I are both related to people we match in common. Said another way, if ER and I both match someone, say Susan, a grid now displays how I’m related to Susan and how ER is related to Susan according to Ancestry’s DNA prediction calculations. I also see how much DNA our shared match, Susan, shares with each of us.

Ancestry has calculated my estimated relationship to my first match, Susan, as my First-cousin-1-time-removed (1C1R) or Half-first-cousin, which is genetically equivalent, on my paternal side.

Ancestry has estimated that ER is also the 1C1R of Susan and they share 395 cM of DNA. How ER is related to Susan, and how much DNA they share, is new information that I didn’t have access to before ProTools.

Ancestry had already calculated that ER and I are Half-1st-cousins-two-times-removed.

Viewing ThruLines shows me that ER is my Half-1st-cousin-once-removed, so either the relationship estimate (based on DNA only) or ThruLines (based on trees) is inaccurate, or maybe both. However, they are both close to each other.

Using the trees of both ER and Susan, if they have trees, helps immensely in working out relationships. If Susan is ER’s first cousin once removed, that means that she shares a common grandfather with ER and with me. They are both paternal side matches and some flavor of first cousin to me, so that means our common ancestor has to be William George Estes.

Now that I can see how my matches are related to each other, I can easily work out the possibilities of how the three of us are related – even without seeing anyone’s trees or ThruLines.

Of course, in more distant generations, it’s much more difficult to sort out relationships without trees. That also means that multiple shared relationships are important, and you’re likely to find links among several testers to common ancestors.

I finally solved one pesky relationship that has been bugging me for a very long time. My match’s mother was identified as such, which led to additional and closer shared matches that helped solve the mystery.

Caution – Children’s Names and Relationships Exposed

Given Ancestry’s previous privacy policies, I was surprised to see that the names of my matches’ living children (or parents) are identified as such. Of course, I’m presuming here that “child” means 18 or older per Ancestry’s Terms and Conditions.

Here are two examples of shared matches with their relationship to my match clearly identified as their child.

This isn’t an anomaly or a bug – it’s just how the feature works.

Under the circumstances, this makes me uncomfortable given that my cousin, the parent, may NOT have ProTools and has absolutely NO IDEA that his matches with ProTools can see the name of his daughter and son and that they are identified as his children.

I’m not upset about the enhanced ProTools shared match feature itself. Conversely, I love it. I’m concerned that people without ProTools don’t realize this information is revealed, because it wasn’t previously. Before ProTools, no one would ever have a reason to suspect that anyone could identify someone on Ancestry as their child.

This seems like a significant policy shift for Ancestry, who has traditionally been extremely careful about not providing identifying information about living relatives. I’m surprised this feature was implemented without informing customers who may be affected or without perhaps obtaining opt-in for that level of exposure.

Then, it occurred to me that maybe my cousin’s children are now deceased.

I checked my cousin’s tree to see if his children’s names were revealed there, indicating they had passed away. Neither his name nor those of his children are provided in his tree, so I’m presuming they are all alive and well. That’s a relief.

Given that Ancestry has steadfastly refused to provide a chromosome browser for years due to privacy concerns, I’m actually shocked to see a child’s name and identifying relationship revealed. A chromosome browser reveals much less.

Disparity

Placing this enhanced Shared Match feature of ProTools behind a paywall, meaning not providing it to everyone who took a DNA test, creates a significant disparity between the ProTool subscribers and those without.

  • In some other countries, ProTools isn’t available yet.
  • Many people don’t check results regularly and would have no idea that ProTools even exists.
  • People who don’t subscribe to ProTools won’t know that people who do subscribe can view this information because it wasn’t previously available.
  • People who have others manage their DNA kit are entirely unaware.

If you don’t subscribe to ProTools, how would you ever know that your matches with ProTools have access to this information?

People who don’t have access to ProTools shared matches, meaning those who don’t live in the US, don’t subscribe to ProTools, don’t sign in regularly, or have someone else manage their DNA kit, have absolutely no idea that all of their matches who subscribe to ProTools now have access to the names and confirmed relationships of their children and close relatives who have also taken DNA tests.

I was unable to find any way to opt out of having a parental or close relationship revealed to shared matches. Even if the relationship wasn’t noted as “son” or “daughter,” based on the amount of shared DNA, a parental relationship is obvious. This is relevant not just for your test but also for any tests you manage for others.

I hope that Ancestry informs its customers about this change. I really like the new enhanced shared match feature, and I certainly don’t want to jeopardize it. The community has waited a very long time for additional information that helps us identify common ancestors and figure out how and where our matches fit into our tree.

However, everyone who has taken a DNA test needs to be informed so that they understand the privacy changes and the additional information now provided to shared matches who subscribe to ProTools.

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Great News – Both e-Pub and Print Version of “The Complete Guide to FamilyTreeDNA” Now Available Worldwide  

  • Anyone, anyplace, can order the full-color, searchable, e-pub version of The Complete Guide to FamilyTreeDNA – Y-DNA, Mitochondrial, Autosomal and X-DNA from the publisher, Genealogical.com, here.
  • Customers within the US can order the black and white print book from the publisher, here.
  • Customers outside the US can order the print book from their country’s Amazon website. The publisher does not ship print books outside the US due to customs, shipping costs, and associated delays. They arranged to have the book printed by an international printer so that it can be shipped directly to Amazon for order fulfillment without international customers incurring additional expenses and delays. If you ordered the book previously from Amazon and a long delivery time was projected, that should be resolved now and your book should be arriving soon.

Comprehensive

This book is truly comprehensive and includes:

  • 247 pages
  • More than 267 images
  • 288 footnotes
  • 12 charts
  • 68 tips
  • Plus, an 18-page glossary

To view the table of contents, click here. To order, click here.

Thank you, everyone, for your patience and your support.

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I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase your price but helps me keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

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Complete Guide to FamilyTreeDNA Released in Hardcopy

Just what many of you have been waiting for! The hardcopy print version of the Complete Guide to FamilyTreeDNA has just been released.

As shown in the table of contents below, The Complete Guide to FamilyTreeDNA contains lots of logically organized information! It includes basic education about genetic genealogy and how it works, instructions on using the FamilyTreeDNA tests and tools, plus an extensive glossary.

Enjoy!

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Announcing: The Complete Guide to FamilyTreeDNA; Y-DNA, Mitochondrial, Autosomal and X-DNA

I’m so very pleased to announce the publication of my new book, The Complete Guide to FamilyTreeDNA – Y-DNA, Mitochondrial, Autosomal and X-DNA.

For the first time, the publisher, Genealogical.com, is making the full-color, searchable e-book version available before the hardcopy print version, here. The e-book version can be read using your favorite e-book reader such as Kindle or iBooks.

Update: The hardcopy version was released at the end of May and is available from the publisher in the US and from Amazon internationally.

This book is about more than how to use the FamilyTreeDNA products and interpreting their genealogical meaning, it’s also a primer on the four different types of DNA used for genealogy and how they work:

  • Autosomal DNA
  • Mitochondrial DNA
  • Y-DNA
  • X-DNA

There’s a LOT here, as shown by the table of contents, below

This book is chocked full of great information in one place. As an added bonus, the DNA glossary is 18 pages long.

I really hope you enjoy my new book, in whatever format you prefer.

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Ancestry’s ThruLines and Shared Matches Now Require a Subscription

Ancestry informed us a few weeks ago that they were changing their platform and that some existing tools would soon be behind a subscription paywall.

I wrote about some changes in the article, Ancestry Updates Ethnicity, Introduces New Features and Pushes Some Behind Paywall.

A few weeks later, another banner appeared saying that everything “beneath the banner” would soon require a subscription of some type, meaning either DNAPlus or a full Ancestry Subscription.

Because Shared Matches was displayed above the banner, I didn’t think that Shared Matches would be behind the paywall, but I was wrong. Trees also require a subscription for DNA testers, but Ethnicity does not.

Truthfully, I’m not surprised by the more advanced features being placed behind a subscription paywall in addition to the price of the test, although I don’t like it. However, I’m shocked that Shared Matches would be restricted. I always viewed Shared Matches as a way to engage new testers just sticking their toe in the water beyond ethnicity results.

Effective now, if you purchase or purchased (in the past) a DNA test and you don’t have a subscription with Ancestry, or your subscription expires, you will be able to view 3 shared matches and no trees. If you want to see more, you have to either purchase their DNAPlus subscription or a regular Ancestry subscription.

So, technically, not all shared matches are behind the paywall, just all except 3.

Let’s sort this out.

First, let’s talk about what this isn’t.

DNAPlus is NOT ProTools

Do not confuse DNA features requiring a minimal DNAPlus subscription with yet another recently-introduced Ancestry feature called ProTools.

ProTools costs $10 per month, is not DNA-related, and includes a Tree Checker, Charts and Reports, Advanced Filters, and Map Views. ProTools is an add-on and requires a full subscription before you can additionally subscribe to ProTools.

This article is not about ProTools.

DNA Features – What’s In and What’s Out?

I fully realize that Ancestry customers expected to continue receiving the features included with an AncestryDNA test when it was purchased, with or without an Ancestry subscription, but that’s not the case anymore.

Ancestry provides this explanatory information in their FAQ.

Don’t shoot the messenger – meaning me. I’m just here to help you sort this out, so let’s review what’s in and what’s out.

Remaining included DNA features for everyone, with or without a subscription, are:

  • Ethnicity estimates
  • DNA communities
  • DNA matches
  • Ability to message matches
  • Ability to compare origins or communities with your matches

Restricted features without a subscription include:

  • Shared matches, which are now limited to 3
  • You can see IF a match has a family tree, its size, and if it’s public or private, but you can’t view the tree’s contents without a subscription

Features requiring a subscription include:

  • Viewing more than 3 shared matches
  • Viewing the contents of your matches’ trees
  • Matching surnames through 7 generations
  • Matching ancestor birthplaces in public trees
  • Common ancestors in trees through 7 generations, which is the link to ThruLines
  • ThruLines, also through 7 generations

All of the SideView™ related features are also subscription-only. You must designate a parental “side” for these features to work. I wrote about how to do that in the article Ancestry’s SideView™ – Dividing Your Ethnicity in Two. Those features are:

  • Ethnicity by parent
  • Matches by parent
  • Communities by parent
  • Traits by parent
  • Chromosome painter (not to be confused with a chromosome browser, which Ancestry does not have)

What is included or excluded in Traits differs depending on when you purchased the Traits test or the upgrade, so I’m not addressing those tests here.

Ancestry DNA Memberships

Ancestry has compiled a chart showing what’s included and what features require a subscription, which they call a membership. DNAPlus includes DNA features. The family history membership includes DNAPlus features and genealogy records.

That page also includes a brief FAQ sheet.

Exception – Shared DNA Results

The exception to the required subscription scenario is if a tester has shared their DNA results with someone who has a membership. The person WITH THE MEMBERSHIP can see the full results, even though the tester cannot if they don’t have a membership.

I have a full membership, and one of my relatives, who is deceased, shared their DNA results with me before he joined our ancestors.

I always check his results because I know he hasn’t changed anything and no longer has a paid membership.

This means that if you’ve asked your cousins to test for your benefit – they do NOT need to subscribe unless they want to work directly with their own results aside from looking at the basics listed in the included features. To work with their results more broadly, YOU need to subscribe and have them share their DNA results with you.

They (or you, with appropriate permission settings) need to link their DNA test to “them,” meaning their profile, in their (or your) tree. This option, along with DNA test sharing, is found under Settings.

Please note that if the DNA results are shared and the person has a tree, they also need to share their tree with you as a separate step found under Tree Settings.

Sharing DNA Results

Here are the instructions you need to provide to your cousins to share their DNA results with you.

To share DNA results with someone, click on “Your DNA Results Summary” at the top of your page, and then click on Settings in the upper right-hand corner.

Scroll down to DNA test sharing.

Click on the right arrow.

Then click on “Invite.”

Enter their email or Ancestry username and select the role of the person you’re inviting.

Then just click on the blue Invite button. That person will receive an invitation and can accept or not. For family members who want you to fully manage their test, instruct them to select Manager. Manager and Collaborator both allow you to connect their test to “them” in a tree, including your tree.

Here’s a breakdown of what different role selections of DNA test sharing can do with or to a tester’s DNA test.

Summary

I know this change in Ancestry’s policy is disappointing for many. I certainly can’t explain or defend Ancestry’s decision. I hope other companies don’t follow suit.

The good news is twofold. If you already have a full subscription, and many genealogists do, this does not affect you directly.

If you’ve encouraged or paid for others to test, you can still view their results through your subscription, so nothing is lost to you so long as they share their DNA results and tree with you.

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Pedigree Collapse and DNA – Plus an Easy-Peasy Shortcut

Pedigree collapse can be responsible for you sharing more DNA than expected with another person.

What is pedigree collapse?

Pedigree collapse occurs when you descend from the same ancestor(s) through more than one path. In other words, you descend from those ancestors through two different children. Therefore, when matching with someone else who descends through those ancestors, you may share more DNA than would be expected from that level of relationship on the surface, meaning without pedigree collapse.

Endogamy is different and means that you descend from a community of ancestors who descend from the same group of ancestors. Often out-marriage is discouraged or otherwise impossible, so all of the group of people share common ancestors, which means they often match on segments without sharing close ancestors. Examples of descent from endogamous populations are Jewish, Amish, Brethren, Acadian, Native Hawaiian, Māori, and Native American people, among others.

I wrote about the difference between pedigree collapse and endogamy in the article, What’s the Difference Between Pedigree Collapse and Endogamy?

I’ve also written about endogamy in the following articles:

Degrees of Consanguinity

If you’re a genealogist, and especially if you’ve worked with Catholic church records, you’ve probably heard of “degrees of sanguinity,” which are prohibited blood relationships in marriage. For example, siblings are prohibited from marrying because they are too closely related, according to church doctrine.

By SVG remake by WClarke based on original by User:Sg647112c – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=54804980

Today, we think of the genetic results of inbreeding, but originally, relationships (and consanguinity) also had to do with inheritance.

Essentially, marriages are prohibited by degree of sanguinity, and that degree is calculated based on this relationship chart. Prohibited degrees of consanguinity changed over time. Sometimes, a priest granted dispensation for a couple to wed who was of a prohibited degree of sanguinity. That’s a genealogy goldmine because it tells you where to look for common ancestors. It also tells you something else – that you may share more DNA with other descendants of that couple than one would otherwise expect.

More Than You Ever Expected

Recently, I’ve been working with an academic research team on a very interesting ancient DNA case that involves pedigree collapse. Doing the genealogy and genetic work on how much DNA was expected in a match without pedigree collapse, and how much was expected with pedigree collapse, was very interesting.

The team was working to confirm relationships between people in a cemetery. The burials shared more DNA than anticipated for who the people were believed to be. Enter pedigree collapse.

I can’t disclose the circumstances just yet – but I will as soon as possible. It’s an extremely interesting story.

We needed to ensure that readers, both academic and more generally understood pedigree collapse and our calculations. Why did burials share higher than expected DNA than indicated by the expected relationships? This puzzle becomes much more interesting when you add in pedigree collapse.

Academic researchers and scientists have access to models and mathematical algorithms that normal air-breathing humans don’t have easy access to.
So, what do you do if you and a match have a known pedigree collapse in your tree? How much DNA can you expect to share, and how do you calculate that?

These are all great questions, so let’s take a look.

I’m sharing the PowerPoint slides I prepared for our team on this topic. I’ve removed anything that would identify or even hint at the project and modified the slides slightly for easier consumption.

This presentation has never been given publicly, so you’re first! It seemed a waste to do this work and not share it!

Pedigree Collapse and DNA

Pedigree collapse occurs when you share an ancestor or ancestors through different pathways. In this case, the person at the bottom is the child of parents who were third cousins, but the father’s grandparents were also first cousins.

First cousin marriages were common in the not-too-distant past. Today, you could easily marry your third or fourth cousin and not even realize it unless someone in your family just happened to be a genealogist.

Genealogists use various tools to calculate the expected amount of shared DNA in relationships – first cousins, siblings, or half-siblings, for example. Both the Shared cM Project at DNAPainter and SegcM at DNA-Sci Tools provide tools.

Take a look at the article, DNA: In Search of…Full and Half-Siblings, for some great examples.

First cousins share common grandparents. Their child inherits DNA from two paths that lead back to the same ancestors. Some of that DNA will be the same, meaning the child will or can inherit the same ancestral segment from both parents, and some will be different segments from those ancestors that the parents do not share with each other.

Inheritance – How It Works

Let’s look at inheritance to see how this happens.

Let’s start with full and half-siblings.

Each child inherits half of their DNA from each parent, but not entirely the same half (unless they are identical twins.)

Therefore, full siblings will match on about 50% of their DNA, which is illustrated by the segments on the chromosome browser. However, and this will be important in a minute, about 25% of their DNA is exactly the same, when compared to each other, on the chromosome inherited from their father and mother at the same location.

On the chromosome browser, you can see that three siblings do match. One sibling (the grey background chromosomes) is the person both other full siblings are being compared to, in the example above.

What you can’t determine is whether they share the exact same DNA on both their mother and father’s Chromosome 1, where the matches overlap, for example. We know they both match their sibling, but the top person could match the sibling due to a match from their paternal chromosome in that location, and the bottom person could match due to their maternal chromosome. There’s no way to know, at least not from that view.

The areas where the siblings share exactly the same DNA on both their maternal and paternal chromosome, both, with each other are called Fully Identical REgions (FIR), as compared to Half Identical Regions (HIR) where the siblings match on either their maternal or paternal copy of the chromosome, but not both.

23andMe used to provide a tool that displayed both types of matches.

Since the data exposure incident at 23andMe, they no longer provide this lovely tool, and since that help page is now gone as well, I doubt this view will ever be returned. Fortunately, I grabbed a screenshot previously.

The dark purple segments are fully identical, meaning that these two full siblings match on both their maternal and paternal chromosomes in that location. The magenta are half identical, which means they match on EITHER the maternal or paternal chromosome in that location but not on both chromosomes. Of course, no color (light grey) means there is no match at that location.

Please note that because 23andMe counts fully identical regions (FIR) twice, their total matching cMs are elevated. The other companies do NOT count those regions twice.
GEDmatch also shows both full and half-identical regions as described more fully, here.

In this full-sibling example from GEDmatch, the green segments are fully identical regions across both the maternal and paternal chromosomes.

The definition of FIR is that two people match on both their mother’s and father’s DNA on the same chromosome. Therefore, in following generations, there technically should not be FIR matches, but in some instances we do find FIR matches outside of full siblings.

Moving down another generation, first cousins may share SOME fully identical DNA, especially if they are from an endogamous population or their mothers are related, but less, and it’s generally scattered.

Here’s my Mom’s GEDmatch comparison to her first cousin. The purple-legend segment shows a match, and the green within that match shows fully identical locations.

You can easily see that these are very scattered, probably representing “chance” or population-based fully identical matching locations within a segment. Comparatively, the green FIR segments for full siblings are dense and compact, indicating a segment that is fully identical.

Evaluating matches for dense FIR segments (known as runs of homozygosity – ROH) is a good indicator of parental relatedness.

Double Cousins

Of course, if these people were double first cousins, where the wives of the siblings were sisters to each other – the first cousins would have large patches of dense green FIR segments.

First cousins share grandparents.

Double first cousins occur when two people share both sets of grandparents, meaning that brothers marry sisters. Normal first cousins share about 12.5% of their DNA, but double first cousins share about 25% of their DNA.

In this case, Sharon and Donna descend from two brothers, James and Henry, who were sons of Joseph and Jane. In this scenario, James and Henry married unrelated women, so Sharon and Donna are first cousins to each other.

Double first cousins share both sets of grandparents so they would inherit FIR from both sets of siblings.

You need to be aware of this, but for now, let’s stick with non-double relationships. You’re welcome!

DNA Inheritance

Here’s a different example of DNA inheritance between two siblings.

  1. You can see that in the first 50 cM segment, both siblings inherited the same DNA from both parents, so they match on both their mother’s and father’s chromosomes. They match on both the 50 cM green and 50 cM pink segments. 23andMe would count that as 100 cMs, but other vendors only count a segment IF it matches, NOT if it matches twice. So, other vendors count this as a 50 cM match.
  2. In column two, these two people don’t match at all because they inherited different DNA from each parent. In this example, Person 1 inherited their maternal grandmother’s segment, and Person 2 inherited their maternal grandfather’s segment.
  3. In column three, our siblings match on their paternal grandmother’s segment.
  4. In column four, no match again.

How much can we expect to inherit at different levels – on average?

Different tools differ slightly, and all tools provide ranges. In our example, I’ve labeled the generations and how much shared DNA we would expect – WITHOUT pedigree collapse.

Ancestral couple Inherited cM Inherited %
Gen 1 – Their children 3500 cM 50
Gen 2 – Grandchildren 1750 cM 25
Gen 3 – Great-Grandchildren 875 cM 12.5
Gen 4 – GG-Grandchildren 437.5 6.25
Gen 5 – GGG-Grandchildren 218.75 3.125
Gen 6 – GGGG-Grandchildren 109.375 1.5625
Gen 7 – GGGG-Grandchildren 54.6875 .078125

Please note that this is inherited DNA, not shared (matching) DNA with another person.

Adding in pedigree collapse, you can see that we have three Gen 1 people involved, three Gen 2 descendants, and two Gen 3 and Gen 4 people.

Each of those people inherit and pass on segments from our original couple at the top.
We have three distinct inheritance paths leading from our original couple to Gen 5.
We have a first cousin marriage at Gen 2, at left, which means that their child, Gen 3, will have an elevated amount of the DNA of their common ancestors.

In Gen 4, two people marry who both descend from a common couple, meaning their child, Gen 5, descends from that couple in three different ways.

Did your eyes just glaze over? Well, mine did, too, which is why I had to draw all of this out on paper before putting it into PowerPoint.

The Gen 5 child inherits DNA from the ancestral couple via three pathways.
The next thing to keep in mind is that just because you inherit the DNA from an ancestor does not mean you match another descendant. Inheritance is not matching.

You must inherit before you can match, but just because you and someone else have inherited a DNA segment from a common ancestor does not guarantee a match. Those segments could be in different locations.

Categories of DNA

When dealing with inheritance and descent, we discuss four categories of DNA.

  • In the first generation, full siblings will, in about 25% of their locations, share the same DNA that has been inherited from both parents on the same chromosome. In other words, they match each other both maternally and paternally at that location. Those are FIR.
  • The DNA you inherit from an ancestor.
  • The DNA that both you and your cousin(s) inherit from a common ancestor and match on the same location. This is shared DNA.
  • The DNA that both you and your cousin(s) inherit from a common ancestor, but it’s not in the same location, so you do not match each other on that segment. Just because you inherit DNA from that ancestor does not necessarily mean that your cousin has the same DNA from that ancestor. This is inherited but not shared.

Inheritance is Not The Same as Matching

Inheritance is not the same thing as matching.

Inheriting our ancestor’s DNA isn’t enough. We need to match someone else who inherited that same segment in order to attribute the segment to that specific ancestor.

Depending on how close or distant the relationship, two people may share a lot of DNA (like full siblings), or one segment in more distant matches, or sometimes none at all. As we reach further back in time, we inherit less and less of our increasingly distant ancestors’ DNA, which means we match increasingly fewer of their descendants. I wrote about determining ancestral percentages in the article,  Ancestral Percentages – How Much of Them is in You?

Based on how much DNA we share with other known relatives, we can estimate relationships.

Pedigree collapse, where one descends from common ancestors more than once, increases the expected amount of inherited DNA, which in turn increases the probability of a shared match with other descendants.

Ancestral Couple Matching Between Shared DNA ~cM Shared DNA ~% Range (Shared cM Project) FIR – Identical DNA
Generation 1 Full Siblings 2600 50 1613-3488 25%
Generation 2 First Cousins 866 12.5 396-1397 0
Generation 3 Second Cousins 229 3.125 41-592 0
Generation 4 Third Cousins 73 0.78125 0-234 0

Here’s an example through third cousins, including expected FIR, fully identical regions where full siblings match each other on both their maternal and paternal chromosomes in the same location.

I provided a larger summary chart incorporating the information from public sources, here, minus FIR.

Of course, double cousins, where two pairs of siblings marry each other, represent another separate level of complexity. DNA-Sci’s Double Cousin Orogen explains this here and also provides a tool.

Double cousins, meaning when two pairs of siblings marry each other, are different from doubly related.

Doubly related means that two people descend from common ancestors through multiple paths, meaning multiple lines of descent. Doubly related is pedigree collapse. Double cousins is pedigree collapse on steroids.

Pedigree Collapse, aka Doubly Related

Calculating expected inherited DNA from multiple lines of descent is a bit more challenging.

A handy-dandy chart isn’t going to help with multiple relationships because the amount of expected shared DNA is based on the number of and distance of relationships.

Please note that this discussion excludes X-DNA matching which has its own inheritance path.

It’s time for math – but I promise I’ll make this relatively easy – pardon the pun.

What’s Behind the Math?

So, here’s the deal. I want you to understand why and how this works. You may not need this information today, but eventually, you probably will. This is one of those “refer back to it” articles for your personal library. Read this once as a conceptual overview, then read it again if you need to work through the relationships.

This is easy if you take it one step at a time.

First, we calculate each path separately.

In the first generation, full siblings inherit identical (FIR) DNA on both their mother’s and father’s chromosomes.

In the second generation, the male inherits the maternal segment, and the female inherits the paternal segment.

In the third generation, their child inherits those segments intact from both of their parents. The child inherits from the ancestral couple twice – once through each parent.

In generation 1, those two segments were FIR, fully identical regions. Both of those men married unrelated wives. When their children, Gen 2, were born, they had either the maternal or paternal segment from their father because they had an entirely different segment in that location from their mother.

However, the child in Gen 3 inherited the original green segment from their father and the original pink segment from their mother – reuniting those FIR segments in later generations.

First Cousin’s Child

Let’s calculate the inheritance for the child of those two first cousins who married.

Ancestral couple Inherited cM Inherited %
Gen 3 – Great-Grandchildren 875 cM 12.5
Gen 3 – Great-Grandchildren 875 cM 12.5
Total 1750 cM 25

Normally, a Gen 3 person inherits roughly 875 cM, or 12.5% of their great-grandparent’s DNA. However, since their grandparents were first cousins, they inherit about twice that amount, or 1750 cM.

While a Gen 3 person inherits as much as a grandchild (25%) normally would from the original couple, they won’t match on all of that DNA. When matching, we need to subtract some of that DNA out of the equation for two reasons:

  • In the first generation, between siblings, some of their DNA was fully identical and cannot be identified as such.
  • In the second generation, they will each have some parts of the ancestral couple’s DNA that will not match the other person. So, they inherit the same amounts from their common ancestors, but they can only be expected to match on about 25% of that amount two generations later.

However, the child of first cousins who marry inherits more DNA of the common ancestors than they would if their parents weren’t related. It’s just that some of that DNA is the same, potentially on the maternal and paternal chromosomes again, and some won’t match at all.

While matching DNA is the whole point of autosomal DNA testing, fully identical DNA matching regions (FIR) cannot be identified that way. For the most part, other than identifying full and half-siblings, sometimes pedigree collapse, and parent-relatedness, fully identical DNA isn’t terribly useful for genealogy. However, we still need to understand how this works.

It’s OK if you just want to say, “I know we’ll share more DNA due to pedigree collapse,” but if you want to know how much more to expect, keep reading. I’d really like for you to understand use cases and be able to track those segments.

Remember, we will learn a super-easy shortcut at the end, so for now, just read. It’s important to understand why the shortcut works.

Sibling Inheritance Versus Matching

In order to compare apples to apples, sometimes we need to remove some portion of DNA in our calculations.

Remember story problems where you had to “show your work”?

Calculating Expected DNA

Here’s the step-by-step logic.

Ancestral couple Inherited Non-Identical cM Inherited %
Gen 1 first son 3500 50
Gen 1 second son 3500 50
Less identical segments (FIR) -1750 (subtracted from one child for illustration) 25
Gen 2 son 1750 25
Gen 2 daughter married Gen 2 son 875 12.5
Gen 3 – Their child path through Gen 2 son 875 cM 12.5
Gen 3 – Their child path through Gen 2 mother 437.5 cM 6.25
Their child total without removing identical segments 1750 cM 25
Their child total after removing identical segments 1312.5 18.75

Category cMs Most Probable Degree Relationship
No Pedigree Collapse 875 98% Great grandparent or great-grandchild, great or half aunt/uncle, great or half niece/nephew, 1C 3
Pedigree Collapse without identical segment removal 1750 100% Grandparent, grandchild, aunt/uncle, half-sibling, niece/nephew 2
Pedigree Collapse after identical segment removal 1312.5 56% grandparent, grandchild, aunt/uncle, niece/nephew, half-sibling 2

Just because you HAVE this much shared (and/or identical) DNA doesn’t mean you’ll match on that DNA.

Next, let’s look at Gen 5 child who inherited three ways from the ancestors.

If you think, “This will never happen,” remember that it did, which is why I was working through this story problem. It’s not uncommon for families to live in the same area for generations. You married who you saw – generally, your family and neighbors, who were likely also family.

Let’s take a look at that 5th generation child.

The more distantly related, the less pedigree collapse affects matching DNA. That’s not to say we can ignore it.

Here’s our work product. See, this isn’t difficult when you take it step by step, one at a time.

Ancestral couple Inherited Non-Identical cM Inherited %
Gen 3 Child total after removing identical segments 1312.5 18.75
Gen 4 father – half of Gen 3 father 656.25 9.375
Gen 5 child – half of Gen 4 father 328.125 4.6875
Gen 5 child – mother’s side calculated from ancestral couple normally 218.75 3.125
Total for Gen 5 Child 546.875 7.8125

Inheritance Ranges

Lots of factors can affect how much DNA a person in any given generation inherits from an ancestor. The same is true with multiple paths from that same ancestor. How do we calculate multiple path inheritance ranges?

As with any relationship, we find a range, or combined set of ranges for Gen 5 Child based on the multiple pathways back to the common ancestors.

Gen 5 Child Inherited Non-Identical cM Inherited %
Without removing either paternal or maternal identical cMs 656.25 9.375
After removing paternal identical cMs only 546.875 7.8125

 

After removing maternal cMs only 546.875 7.8125

 

After removing both paternal and maternal identical cMs 362.50 6.25
Normal Gen 5 no pedigree collapse 218 3.125

What About Matching?

Inheritance and matching are different. Most of the time, two people are unlikely to share all of the DNA they inherited from a particular ancestor. Of course, inheriting through multiple paths increases the likelihood that at least some DNA from that ancestor is preserved and that it’s shared with other descendants.

Two people aren’t expected to match on all of the segments of DNA that they inherit from a particular ancestor. The closer in time the relationship, the more segments they will inherit from that ancestor, which increases the chances of matching on at least one or some segments.

Clearly, pedigree collapse affects matching. It’s most pronounced in closer relationships, but it may also be the only thing that has preserved that ONE matching segment in a more distant relationship.

So, how does pedigree collapse actually affect the likelihood of matching? What can we actually expect to see? Is there a name for this and a mathematical model to assist with calculations?

I’m so glad you asked! It’s called Coefficient of Relationship.

Coefficent of Relationship

My colleague, Diahan Southard, a scientist who writes at YourDNAGuide has authored two wonderful articles about calculating the statistical effects of pedigree collapse.

You can also read another article about the methodology of calculating coefficient of relationship, here, on WaybackMachine.

Diahan is a math whiz. I’m not, so I needed to devise something “quick and dirty” for my own personal use. I promised you a “cheat sheet,” so here’s the methodology.

Two Inheritance Paths – First and Third Cousins

Let’s look at an example where two people are both first cousins and third cousins because their grandparents were also first cousins.

Let’s calculate how these two people are related. They are first cousins and also third cousins.

When calculating the effects of pedigree collapse, we calculate the first relationship normally, then calculate the second relationship and add a portion of the result.

Here’s the math.

Using the Shared cM Project for the expected amount of shared DNA for both relationships, we’ve calculated the expected range for this pedigree collapse relationship.

Tying this back to degrees of relatedness.

Let’s look at ways to do Quick Calculations using the publicly available Shared cM charts and my composite tables, here.

Using Average Shared DNA

This first methodology uses average expected amount of shared, meaning matching, DNA. Please note, I’m not necessarily expecting you to DO this now, just read to follow.

Using Average Inherited DNA

Here’s a second method using average inherited DNA, meaning people wouldn’t be expected to match on all of the inherited DNA – just a portion.

You can’t always use the shared cM charts because all relationships aren’t represented, so you may need to use the amount of expected inherited DNA instead of shared DNA amounts.

Methodology Differences

Remember, none of these methodologies are foolproof because DNA inheritance is random. You may also have additional relationships that you’re aware of.

So, what’s the easiest method? Neither, actually. I’ve found an even easier method based on these proven methodologies.

Easy-Peasy Pedigree Collapse Shortcut Range Calculation in 4 Steps

Now that you understand the science and reasoning behind all of this, you can choose from multiple calculation methodologies after drawing a picture of the relevant tree.

You’re probably wondering, “What’s the easiest way to do this?”

  • These quick calculation methods are the easiest to work with for non-scientists and non-math whizzes. These are the calculations I use because, taking into account random recombination, you can’t do any better than get close.
  • Also, remember, if you’re dealing with double relationships, meaning double first cousins, you’ll need to take that into consideration, too.
  • If endogamy is involved, your matches will be higher yet, and you should use the highest calculations below because you need to be on the highest end of the range – and that may still not be high enough.

In these Easy-Peasy calculations, you calculate for the lowest, then the highest, and that’s your range. Please note that these are options, and truly, one size does not fit all.

  1. For the lowest end of the range, simply use the average of the highest relationship. In this case, that would be 1C, which is 866 cM. Remember that you may not share DNA with third cousins. 10% of third cousins don’t share any DNA, and 50% of fourth cousins don’t.
  2. For the highest end of the range, find the second relationship in the Shared cM chart, divide the average by half, and add to the value from the closest relationship. In this case, half of the 3C value of 76 is 38.
  3. Add 38 to 866 for the highest end of the range of 904.
  4. If there’s yet another path to ANY shared ancestor, add half that amount too to calculate the high end of the range – unless it’s 4C or more distant, then don’t add anything.

You can see that this easy-peasy range calculation for pedigree collapse compares very well to the more complex but still easy calculations.

  • Easy-peasy calculation: 866-904
  • Other calculation methods: 850-903
  • For this same relationship combination, Diahan’s statistical calculation was 850 cM.

Back to Genealogy

What’s the short story about how pedigree collapse affects genealogy?

Essentially, in close generations, meaning within a few generations of two first cousins marrying, descendants can expect to inherit and share significantly more DNA of the common ancestors, but not double the amount. As we move further away from those marriages in time, the effect becomes less pronounced and more difficult to detect. You can see that effect when calculating multiple paths where at the fourth cousin level, or more distant, those cousins have a 50% or greater possibility of not sharing DNA segments.

Of course, with multiple paths to the same ancestor, your chances of inheriting at least some segments from the common ancestor are increased because their DNA descends through multiple paths.

Today, close marriages are much less common and have been for several generations in many cultures, so we see fewer instances where pedigree collapse makes a significant difference.

Within a population or group of people, if pedigree collapse becomes common, meaning that there are multiple paths leading back to common ancestors, like our three-path example, DNA segments from the common ancestors are found among many people. Significant pedigree collapse becomes endogamy, especially if marriage outside of the group is difficult, impossible, or discouraged.

Normally, pedigree collapse is not recorded in actual records. It’s left to genealogists to discover those connections.

The exception, of course, is those wonderful Catholic parish records where the priest granted dispensations. Sometimes, that’s our only hint to earlier genealogy. In the case of the marriage of Marie-Josesphe LePrince to Jacques Forest, the priest wrote “dispense 3-3 consanguinity,” which tells us that they shared great-grandparents. It also tells us that their grandparents were siblings, that the bride and groom were second cousins, and that their children and descendants inherited an extra dose of DNA from their common great-grandparents.

How does that affect me today? Given that I’m their seventh-generation descendant – probably not at all. Of course, they are Acadian, and the Acadians are highly endogamous, which means I match many Acadians because all Acadians share the DNA of just a few founders, making it almost impossible to track segments to any particular ancestor. If it weren’t for endogamy, I would probably match few, if any, of their descendants.

Now, when you see those Catholic church dispensations or otherwise discover pedigree collapse, you can be really excited, because you understand the effects of pedigree collapse and how to calculate resulting matches! You might, just might, have retained a DNA segment from those ancestors because you inherited segments through multiple paths – increasing the probability that one survived.

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