If you’re doing DNA tests for family history, you may see lots of predicted cousin matches: 2nd, 3rd, 4th, etc…..But what does that predicted genetic relationship actually mean? Learn about centimorgans, the powerful genetic genealogy unit of measure, and how it helps your research.
How DNA Tests Measure Genetic Relationships
When we are looking at genetic relationships, there are also many ways we can measure them. But ultimately, we want the testing company to tell us how likely it is that a particular individual shares a single, recent common ancestor with us. One factor in this calculation is to take into account the total amount of DNA we share with that match.
Currently, all the testing companies are reporting this sum in centimorgans (cMs). Every company reports to you the total number of shared cMs, as outlined below.
AncestryDNA: Click on the match to access the personal profile page for that match. In the second section, under Predicted Relationship, you will see the confidence level. To the right of the confidence level, you will see a grey circle with a little “i” in it. Clicking there will show you the total amount of shared cMs as well as how many pieces of DNA you share.
Family Tree DNA: On the main match page for your Family Finder results, you will see the total amount of shared cMs in the third column.
23andMe: You can see the percentage of shared DNA from the main DNA Relatives home page. To convert the percentage into centimorgans, just multiply your percentage by 68 (that will at least get you close). You can also see total shared cMs in the chromosome browser tool (go to Tools > DNA Relatives > DNA).
MyHeritageDNA: The total amount of shared DNA is shown on the main match page under the title Match Quality. MyHeritage also has a new DNA Match Review page. Click here to read more about that.
Centimorgan: A Genetic “Crystal Ball”
It is very tempting to think of a cM just like you would think of an inch or a centimeter, and for all practical purposes, that is okay. But it is actually much more complicated than that.
A cM is actually more like a crystal ball: it helps us predict how likely a piece of DNA looks exactly as it did a generation ago. This, in turn, helps us calculate how far back we should be looking for the common ancestor between two people.
But for our practical purposes, you can use the total amount of shared DNA, in combination with this chart compiled by Blaine Bettinger and the Shared cM Project, to better assess your genealogical relationship with your match based on your genetics.
To use the chart, take the total amount of shared DNA you have with a match, and look up that number in the chart to get an idea of what kind of genealogical relationship might best fit the genetics that you see. For example, if I share 69 cM with my match, we might be third cousins. But we might also be second cousins once or twice removed.
How do you figure out which one? Simply put: do genealogy research! It’s time to use traditional records and research skills to better understand the genetic clues in your family history mysteries.
My series of DNA quick reference guides can help you get the most out of your DNA tests for family history. I definitely recommend the value-priced bundle of all 10 guides. But I especially recommend the guides listed below if you’re to the point where you’re trying to understand what genetic relationships mean:
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I was honored to speak at the first MyHeritage LIVE conference in Oslo, Norway in 2018. After another rousing success in Amsterdam in 2019, the event is coming to Israel in 2020. I’ll be there speaking along with many of your favorites. MyHeritage LIVE is an event like no other that you won’t want to miss. Here are all the details from the folks at MyHeritage.
From Daniel Horowitz, Genealogy Expert at MyHeritage:
Following the success of MyHeritage LIVE 2018 and 2019, I am delighted to announce that our third annual MyHeritage LIVE conference will take place from 25–26 October 2020 at the Hilton Tel Aviv in Israel!
As one of the most celebrated genealogy events of the year, MyHeritage LIVE brings together family history enthusiasts, top international experts, and MyHeritage staff for two days of fascinating lectures covering the latest topics in genealogy and DNA. Each year, hundreds of MyHeritage users from around the world attend.
The venue is situated right on the Tel Aviv coastline with breathtaking views of the Mediterranean Sea. This year’s conference presents you with a wonderful opportunity to connect with fellow genealogy enthusiasts and tour a unique and beautiful country steeped in ancient history.
In addition to a plenary session from MyHeritage Founder and CEO Gilad Japhet, there will be multiple lectures, panels, and workshops covering genealogy and DNA, as well as sessions from local speakers covering Israeli resources and Jewish genealogy.
We’ve lined up an excellent array of international speakers including:
Roberta Estes,
Thomas MacEntee,
Dick Eastman,
Diahan Southard,
and Lisa Louise Cooke.
Joining them from Israel will be Garri Regev and Rony Golan along with others to be announced soon.
From the MyHeritage team, you’ll also hear from Maya Lerner, VP Product; Schelly Talalay Dardashti, U.S. Genealogy Advisor; Michael Mansfield, Director of Content Operations; Daniel Horowitz, Genealogy Expert; and more.
We’d be delighted if you share this news with your followers and let them know that they can register now on the MyHeritage LIVE 2020 website to secure early bird pricing of $100 per ticket.
“MyHeritage LIVE 2020 will take place on October 25–26, 2020 at the Hilton Tel Aviv. Set in landscaped Independence Park, this upscale hotel is a short 8-minute walk from the Mediterranean beachfront and just 5 km from the Tel Aviv-Savidor Center train station.
If you haven’t visited Tel Aviv yet, now is your chance to experience a beautiful, vibrant city that’s known as a “city that never sleeps,” making it a perfect fit for night owl genealogists who toil late into the night to work on their research. Explore the past and experience new cultures in a truly unique country steeped in ancient history.”
Tickets
Conference tickets include access to lectures, workshops, coffee breaks, lunches, and the MyHeritage party, all of which you don’t want to miss!
Past events
Both MyHeritage LIVE 2018 in Oslo, Norway, and MyHeritage LIVE 2019 in Amsterdam, the Netherlands received tremendous praise from conference participants, who declared the events some of the best conferences they’ve ever attended.
There were three different tracks: DNA, genealogy, and hands-on workshops. Riveting talks by guest speakers and MyHeritage staff captivated full audiences. MyHeritage Customer Support representatives were on hand throughout the conference to provide comprehensive, hands-on support.
Watch the 2019 Highlights:
Watch My Presentation from MyHeritage LIVE 2018
How to Find Your Family in Newspapers with SuperSearch:
Opening your AncestryDNA account to find a New Ancestor Discovery can be a bit like the experience my nine-year old had at the beach today. He noticed something unusual in the sand on his way down to the beach and excitedly used his hands to unearth the treasure. However, it turned out to be a Captain Hook figurine long lost by another (likely much younger) beach-goer. His initial excitement quickly dissipated. He was disappointed as he had clearly found something he did not need or want.
I have heard from many of you that are confused and disappointed with Ancestry’s attempts to merge your genetics and your genealogy. Keep in mind that AncestryDNA matches are only using your genetics. Your DNA Circles and your New Ancestor Discoveries incorporate your linked treeinto your genetic test results.
Lisa recently forwarded me a comment from Kate that perfectly illustrates the confusion I’m talking about. “We had DNA done thru Ancestry,” she writes. “The results [have] made me seriously question what they are showing me. I believe they are using my tree to show me results that are more vague than they are revealing. The latest example they show is a person not related by blood. This family is related by name only (my uncle’s spouse).
“My results from Ancestry show that they use my tree to make matches. Just checked the web page for DNA results. They show numerous matches….Three or 4 contacted me because they were convinced they were related by blood when they may have had a remote tree connection. They contacted me because the DNA results showed they were a 3rd or 4th
cousin, when in fact they would only be a 3rd or 4th cousin in my tree.”
I can see why she’s confused. First, let’s review what an AncestryDNA New Ancestor Discovery (NAD) actually IS. NAD’s are based on the DNA Circle idea created by Ancestry. Remember that a DNA circle is when Ancestry can identify a shared genetic AND genealogical connection between three or more people. Using various standards and measures, they name an ancestor as your connection. This is the ancestor I affectionately call our Party Host. This is the ancestor who passed his or her DNA down to all of their descendants, like tickets inviting them to this party in the future. So, everyone who holds a ticket, AND who has honored that party host ancestor by placing their name in their pedigree chart, is listed as a guest in the form of a DNA circle connection. (Click here to read a blog post about this concept.)
The New Ancestor Discoveries just take that one step further. The NAD is an attempt to find ticket holders who have not yet taken that extra step and added that important Party Host ancestor to their family tree. The NAD is like a nudge, inviting us to double check our family tree to see if this particular ancestor might need to be added. It is important to remember that a NAD comes only after a DNA circle has already been formed, and there could have been errors in that formation. So the very first thing you need to do with a NAD is to correspond with circle members and double check that the Party Host of the circle, their common ancestor, is correct. Then we can move on to evaluating the NAD.
Ancestry admits on its help pages that there are three reasons why you might get an NAD, and only one is “right” in the way you and I might view it.
The “right” answer comes when the DNA circle was drawn correctly, the Party Host properly identified, and your DNA connection is strong to two or more members of the circle. You are then able to verify through traditional genealogical methods that you are an actual descendant of the Party Host, holding that coveted ticket, shown in blue in this modified image from the AncestryDNA help page.
There are two other alternatives.
First, you are related to the NAD Party Host (the New Ancestor that was discovered) via marriage. In this second example from Ancestry’s help page, we see that your ancestor was married twice. The members of the DNA circle are descendants of her other marriage. Remember, that you do not share DNA with every member of the DNA circle. In this case, you share the purple DNA with a few members of the circle. But there are other members that share the blue. So the super computers at Ancestry first put all the blues together in a circle with the Party Host at the top. Then you come along with purple DNA that matches a few in the circle and their supercomputer erroneously assumes that you too must have been invited to this “blue” party, but in fact, the blue/purple members of the circle are double booked. They have been invited to both the blue and the purple party.
How can you fix this? If you can identify your purple Party Host, then you can add that person to your tree, and the trees of your DNA matches and likely then a new DNA Circle will form with the purple Party Host at its head, and the blue NAD will disappear.
The other situation that many of you are seeing, especially those of you with ancestry from small communities, is demonstrated in Figure 3 of the Ancestry Help page, reproduced here. As you can see, this one is much more complicated. (In fact, the colors I added aren’t even quite accurate, as not all descendants of the blue NAD have the same blue, but rather different shades of blue depending on the segment they received- but this is a story for another post!)
The short of it is, the members of the previously established DNA circle share one single ancestor with each other, but they share multiple separate and distinct ancestors with you. Looking at this chart it seems very clear, but remember, in the database we only see you and the people you match. We cannot tell from the DNA shared which piece came from which ancestor. So, it is very important to check and double check the pedigrees of those in the circle to identify additional shared lines.
The short of it is, these NAD’s are following the guilt by association rule, but in fact, you could be innocent. Just keep in mind the simple principle that you DO share a common ancestor with those members of the circle that you share DNA with. You do NOT necessarily share common ancestry with those in the circle that you do not share DNA with.
The key is to take these NAD’s for what they really are: research suggestions. Keep your expectations low, and then you will be pleasantly surprised when you are able to verify a connection.
Ready to learn more about DNA testing for family history? Click here to watch two video interviews in which Lisa and I chat about genetic genealogy.
My DNA quick reference guides can get you started on your own DNA research, or help you unpuzzle and maximize results you don’t fully understand. Click here to see all six guides: purchase them individually or as value-priced bundles.
When we are looking at genetic relationships, there are also many ways we can measure them. But ultimately, we want the testing company to tell us how likely it is that a particular individual shares a single, recent common ancestor with us. One factor in this calculation is to take into account the total amount of DNA we share with that match.
AncestryDNA: Click on the match to access the personal profile page for that match. In the second section, under Predicted Relationship, you will see the confidence level. To the right of the confidence level, you will see a grey circle with a little “i” in it. Clicking there will show you the total amount of shared cMs as well as how many pieces of DNA you share.
It is very tempting to think of a cM just like you would think of an inch or a centimeter, and for all practical purposes, that is okay. But it is actually much more complicated than that.
