Using Mitochondrial Haplogroups at 23andMe to Pick the Lock

I’ve been writing recently about using haplogroups for genealogy, and specifically, your mitochondrial DNA haplogroup. You can check out recent articles here and here.

While FamilyTreeDNA tests the entire mitochondria and provides you with the most detailed and granular haplogroup, plus matches to other testers, 23andMe provides mid-range level haplogroup information to all testers.

I’ve been asked how testers can:

  1. Locate that information on their account
  2. What it means
  3. How to use it for genealogy

Let’s take those questions one by one. It’s actually amazing what can be done – the information you can piece together, and how you can utilize one piece of information to leverage more.

Finding Your Haplogroup Information

At 23andMe, sign in, then click on Ancestry.

Then click on Ancestry Overview.

You’ll need to scroll down until you see the haplogroup section.

If you’re a female, you don’t have a paternal haplogroup. That’s misleading, at best and I wrote about that here. If you click to view your report, you’ll simply be encouraged to purchase a DNA test for your father.

Click on the maternal haplogroup panel to view the information about your mitochondrial haplogroup.

You’ll see basic information about the haplogroup level 23andMe provides. For me, that’s J1c2.

Next, you’ll view the migration path for haplogroup J out of Africa. Haplogroup J is the great-granddaughter haplogroup of L3, an African haplogroup. Mutations occurred in L3 that gave birth to haplogroup N. More mutations gave birth to R, which gave birth to J, and so forth.

You’ll notice that haplogroup J1c2 is fairly common among 23andMe customers. This means that in my list of 1793 matches in DNA Relatives, I could expect roughly 9 to carry this base haplogroup.

There’s more interesting information.

Yes, King Richard is my long-ago cousin, of sorts. Our common mitochondrial ancestor lived in Europe, but not long after haplogroup J1c migrated from the Middle East.

One of my favorite parts of the 23andMe information is a bit geeky, I must admit.

Scroll back to the top and select Scientific Details.

Scroll down, and you’ll be able to see the haplogroup tree formation of all your ancestral haplogroups since Mitochondrial Eve who is haplogroup L. You can see L3 who migrated out of Africa, and then N and R. You can also see their “sister clades,” in blue. In other words, L3 gave birth to L3a through M, which are all sisters to N. N gave birth to R, and so forth.

On the free Public Mitochondrial Tree, provided by FamilyTreeDNA, you can see the haplogroups displayed in a different configuration, along with the countries where the most distant known ancestors of FamilyTreeDNA testers who carry that haplogroup are found. Note that only people who have taken the full sequence test are shown on this tree. You can still check out your partial haplogroup from 23andMe, but it will be compared to people who don’t have a subgroup assigned today on this public tree.

If you were to take the full sequence test at FamilyTreeDNA, you might well have a more refined haplogroup, including a subgroup. Most people do, but not everyone.

Here’s the second half of the 23andMe haplogroup tree leading from haplogroup R to J1c2, my partial haplogroup at 23andMe.

Here’s the public tree showing the J1c2 haplogroup, and my most refined haplogroup, J1c2f from my full sequence test at FamilyTreeDNA.

If you’re interested in reading more in the scientific literature about your haplogroup, at the bottom of the 23andMe Scientific Details page, you’ll see a list of references. Guaranteed to cure insomnia.😊

You’re welcome!

Using Your Haplogroup at 23andMe for Genealogy

Enjoying this information is great, but how do you actually USE this information at 23andMe for genealogy? As you already know, 23andMe does not support trees, so many times genealogists need to message our matches to determine at least some portion of their genealogy. But not always. Let’s look at different options.

While a base haplogroup is certainly interesting and CAN be used for some things, it cannot be used, at 23andMe for matching directly because only a few haplogroup-defining locations are tested.

We can use basic haplogroup information in multiple ways for genealogy, even if your matches don’t reply to messages.

23andMe no longer allows testers to filter or sort their matches by haplogroup unless you test (or retest) on the V5 platform AND subscribe yearly for $29. You can read about what you receive with the subscription, here. You can purchase a V5 test, here.

To get around the haplogroup filtering restriction, you can download your matches, which includes your matches’ haplogroups, in one place. I provided instructions for how to download your matches, here.

While 23andMe doesn’t test to a level that facilitates matching on mitochondrial alone, even just a partial haplogroup can be useful for genealogy.

You can identify the haplogroup of specific ancestors.

You can identify people who might match on a specific line based on their haplogroup. and you can use that information as a key or lever to unlock additional information. You can also eliminate connections to your matches on your matrilineal line. 

Let’s start there.

Matrilineal Line Elimination

For every match, you can view their haplogroup by clicking on their name, then scrolling down to view haplogroup information.

As you can see, Stacy does not carry the same base haplogroup as me, so our connection is NOT on our direct matrilineal line. We can eliminate that possibility. Our match could still be on our mother’s side though, just not our mother’s mother’s mother’s direct line.

If Stacy’s haplogroup was J1c2, like mine, then our connection MIGHT be through the matrilineal line. In other words, we can’t rule it out, but it requires more information to confirm that link.

Identifying My Ancestor’s Haplogroups

I’ve made it a priority to identify the mitochondrial haplogroups of as many ancestors as possible. This becomes very useful, not only for what the haplogroup itself can tell me, but to identify other matches from that line too.

click to enlarge images

Here’s my pedigree chart of my 8 great-grandparents. The colored hearts indicate whose mitochondrial DNA each person inherited. Of course, the mothers of the men in the top row would be shown in the next generation.

As you can see, I have identified the mitochondrial DNA of 6 of my 8 great-grandparents. How did I do that?

  • Testing myself
  • Searching at FamilyTreeDNA for candidates to test or who have already tested
  • Searching at Ancestry for candidates to test, particularly using ThruLines which I wrote about, here.
  • Searching at MyHeritage for candidates to test, particularly using Theories of Family Relativity which I wrote about, here
  • Searching for people from a specific line at 23andMe, although that’s challenging because 23andMee does not support traditional trees
  • Searching for people who might be descended appropriately using the 23andMe estimated “genetic tree.” Of course, then I need to send a message and cross my fingers for a reply.
  • Searching for people at WikiTree by visiting the profile of my ancestors whose mitochondrial DNA I’m searching for in the hope of discovering either someone who has already taken the mitochondrial DNA test, or who descends appropriately and would be a candidate to test

In my pedigree chart, above, the mitochondrial DNA of John Ferverda and his mother, Eva Miller, T2b, is a partial haplogroup because I discovered the descendant through 23andMe.

I was fairly certain of that match’s identity, but I need two things:

  • Confirmation of their genealogical connection to Eva Miller Ferverda
  • Someone to take the full sequence test at FamilyTreeDNA that will provide additional information

I confirmed this haplogroup by identifying a second person descended from Eva through all females to the current generation who carries the same haplogroup

Now that I’ve confirmed one person at 23andMe who descends from Eva Miller Ferverda matrilineally, and I know their mitochondrial DNA haplogroup, I can use this information to help identify other matches – even if no one responds to my messages.

This is where downloading your spreadsheet becomes essential.

Download Your Matches

Next, we’re going to work with a combination of your downloaded matches on a spreadsheet along with your matches at 23andMe on the website.

I provided step-by-step instructions for downloading your matches, here.

On the spreadsheet, you’ll see your matches and various columns for information about each match, including (but not limited to):

  • Name
  • Segment information
  • Link to tester’s profile page (so you don’t need to search for them)
  • Maternal or paternal side, but only if your parents have tested
  • Maternal haplogroup (mitochondrial DNA for everyone)
  • Paternal haplogroup (Y DNA if you’re a male)
  • Family Surnames
  • Family Locations
  • Country locations of 4 grandparents
  • Notes (that you’ve entered)
  • Link to a family tree if tester has provided that information. I wrote about how to link your tree in this article. The tree-linking instructions are still valid although 23andMe no longer partners with FamilySearch. You can link an Ancestry or MyHeritage tree.

I want to look for other people who match me and who also have haplogroup T2b, meaning they might descend from Eva Miller Ferverda, her mother, Margaret Elizabeth Lentz, or her mother, Johanne Fredericka Ruhle in the US.

To be clear, the mitochondrial DNA reaches back further in time in Germany, but since 23andMe limits matches to either your highest 1500 or 2000 matches (it’s unclear which,) minus the people who don’t opt-in to Relative Sharing, I likely wouldn’t find anyone from the German lines in the 23andMe database as matches. If you subscribe to the V5+$29 per year version of the test, you are allowed “three times as many matches” before people roll off your match list.

On the download spreadsheet, sort on the maternal column.

I have several people who match me and are members of haplogroup T2b.

Upon closer evaluation, I discovered that at least one other person does descend from Eva Miller, which confirmed that Eva’s haplogroup is indeed T2b, plus probably an unknown subclade.

I also discovered two more people who I think are good candidates to be descended from Eva Miller using the following hints:

  • Same haplogroup, T2b
  • Shared matches with other known descendants of Eva Miller, Margaret Lentz or Frederica Ruhle.
  • Triangulation with some of those known descendants

Now, I can look at each one of those matches individually to see if they triangulate with anyone else I recognize.

Do be aware that just because these people have the mitochondrial haplogroup you are seeking doesn’t necessarily mean that you’re related through that line. However, as I worked through these matches WITH the same haplogroup, I did find several that are good candidates for a common ancestor on the matrilineal line based on matches we share in common.

Let’s hope they reply, or they have tested at a different vendor that supports trees and I can recognize their name in that database.

Assign a Side

At 23andMe, one of the first important steps is to attempt to assign a parental side to each match, if possible.

If I can assign a match to a “side” of my tree based on shared matches, then I can narrow the possible haplogroups that might be of interest. In this case, I can ignore any T2b matches assigned to my father’s side.

The way to assign matches to sides, assuming you don’t have parents to test, is to look for triangulation or a group of matches with known, hopefully somewhat close, relatives.

I wrote about Triangulation Action at 23andMe, here.

For example, my top 4 matches at 23andMe are 2 people from my father’s side, and 2 people from my mother’s side, first or second cousins, so I know how we are related.

Using these matches, our “Relatives in Common,” and triangulation, I can assign many of my matches to one side or the other. “Yes” in the DNA Overlap column means me, Stacy and that person triangulate on at least one segment.

Do be careful though, because it’s certainly possible to match someone, and triangulate on one segment, but match them from your other parent’s side on a different segment.

At the very bottom of every match page (just keep scrolling) is a Notes field. Enter something. I believe, unless this has changed, that if you have entered a note, the match will NOT roll off your list, even if you’ve reached your match limit. I include as much as I do know plus a date, even if it’s “don’t know which side.” At least I know I’ve evaluated the match.

However, equally as important, when you download your spreadsheet, you’ll be able to see your own notes, so it’s easy to refer to that spreadsheet when looking at other relatives in common on your screen.

I have two monitors which makes life immensely easier.

Working the Inverse

Above, we used the haplogroup to find other matches. You can work the inverse, of course, using matches to find haplogroups.

Now that you’ve downloaded your spreadsheet, you can search in ways you can’t easily at 23andMe.

On your spreadsheet, skim locations for hints and search for the surnames associated with the ancestral line you are seeking.

Don’t stop there. Many people at 23andMe either don’t enter any information, but some enter a generation or two. Sometimes 4 surnames, one for each grandparent. If you’ve brought your lines to current genealogically, search for the surnames of the people of the lines you seek. Eva’s grandchildren who would carry her mitochondrial haplogroup would include the surnames of Robison, Gordon, and several others. I found two by referencing my descendants chart in my computer genealogy program to quickly find surnames of people descended through all females.

The link to each match’s profile page is in the spreadsheet. Click on that link to see who you match in common, and who they and you triangulate with.

Because each of the people at 23andMe does have at least a partial mitochondrial DNA haplogroup, you may be able through surname searching, or perhaps even viewing matches in common, to reveal haplogroups of your ancestors.

If you’ve already identified someone from that ancestral line, and you’re seeking that ancestor’s mitochondrial DNA, highlight the people who triangulate with the known descendant on your spreadsheet. Generation by generation, search for the surnames of that ancestor’s female grandchildren. I found one line just one generation downstream which allowed me to identify the ancestor’s haplogroup. In other words, the birth surname of my ancestor was missing, and that of her husband, but the surname of one of her granddaughters was there.

That person did indeed match and triangulate with other known descendants.

Sorting by haplogroup, at that point, showed two additional people I was able to assign to Eva’s haplogroup line and confirm through what few tidbits of genealogy the testers did provide.

I started with not knowing Eva’s haplogroup, and now I not only know she is haplogroup T2b, I’ve identified and confirmed a total of 6 people in this lineage who also have haplogroup T2b – although several descend from her mother and grandmother. I’ve also confirmed several others through this process who don’t have haplogroup T2b, but who triangulated with me and those who do. How cool is this?

I’ll be checking at FamilyTreeDNA to see if any of Eva’s T2b descendants have tested or transferred there. If I’m lucky, they’ll have already taken the mitochondrial DNA test. If not, I’ll be offering a mitochondrial DNA full sequence testing scholarship to the first one of those matches to accept.

Is this process necessarily easy?

No, but the tools certainly exist to get it done.

Is it worth it?

Absolutely.

It’s one more way to put meat on the bones of those ancestors, one tiny piece of information at a time.

I’ll be reaching out to see if perhaps any of my newly identified cousins has genealogical information, or maybe photos or stories that I don’t.

Tips and Tools

For tips and tools to work with your mitochondrial DNA haplogroups, read the article Where Did My Mitochondrial DNA Haplogroup Come From?

Please visit the Mitochondrial DNA Resource page for more information.

You can also use Genetic Affairs AutoCluster tool to assist in forming groups of related people based on your shared matches at 23andMe and FamilyTreeDNA.

What Can You Find?

What can you find at 23andMe?

Your ancestor’s haplogroups, perhaps?

Or maybe you can use known ancestral haplogroups as the key to unlocking your common ancestor with other matches.

I found an adoptee while writing this article with common triangulated matches plus haplogroup T2b, and was able to provide information about our common ancestors, including names. Their joy was palpable.

Whoever thought something like a partial haplogroup could be the gateway to so much.

23andMe tests are on sale right now for Mother’s Day, here.

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to 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.

DNA Purchases and Free Transfers

Genealogy Products and Services

Books

Genealogy Research

Misleading 23andMe Paternal Haplogroup Emails For Females

I received an email for a 23andMe kit that I manage stating “Your Paternal Haplogroup Report is waiting for you.” Really? Cool!!!

Only problem is that the tester is a female – and females don’t have a paternal haplogroup available because females don’t have Y DNA.

Clearly, this is just not possible.

Three things crossed my mind:

  1. Erroneous email, as in “oops.” Some marketing person is going to be in a heap of trouble.
  2. Incompetence following the sale of the company. There have been other recent changes that caused me to wonder, although some were reversed.
  3. Bait and switch. Surely not. 23andMe has never been like that, so this is a distant third.

I knew for an absolute fact, beyond any doubt that this close family member is female.

I also realize that any female who receives this email would excitedly check their Paternal Haplogroup report – thinking that maybe, just maybe, some new scientific discovery had been made so they CAN actually see a paternal haplogroup from their own DNA test.

Time to see what’s going on.

I Signed In

I signed in and saw an unopened Paternal Haplogroup report under “Next Reports” at the top of the main page.

click to enlarge

I checked another female kit that I manage, plus my own. The same thing appeared on both of those accounts too.

This e-mail was clearly not an “oops” email inadvertently sent to a female group of testers. It has to be something else.

Sure enough, on the Ancestry tab, if I scroll down, I see these two placards.

click to enlarge image

Maternal Haplogroup, which everyone has, and Paternal Haplogroup, which only males have. Did 23andMe make some kind of mistake? I clicked on the “View Your Report” button for Paternal Haplogroup. It took me to the same page the Paternal Haplogroup link on my main page did.

click to enlarge image

My heart just sank.

Sure enough, it’s a pitch to test another family member, a father or brother. 23andMe explains that no, the female tester really doesn’t have a paternal haplogroup.

So, it IS bait and switch, the least likely scenario I expected. I’m really disappointed. I never thought I’d see the day 23andMe would adopt this type of disingenuous marketing technique.

Why Does This Bother Me So Much?

In general, acquisitions make people uneasy, and 23andMe was acquired in February.

We don’t know what to expect of the new owners, or the direction they will take a company. In this case, the company involved, 23andMe, not only has my DNA, they provide information about my health as part of my test.

Consumers need to be able to have confidence that the information 23andMe provides is accurate. We need to be able to trust them, to believe what they tell us about our DNA results without having to wonder if there is something more, or less, in this case, to the story. In other words, that there’s no ulterior motive in their message.

I grew up on a farm and my old farmer Dad used to tell me that “if someone will lie to you about one thing, they will lie to you about anything.”

I would have NO PROBLEM whatsoever with 23andMe sending an email telling females how to obtain a paternal haplogroup for their paternal line.

There’s a significant difference, though, between that and telling female testers that their “Paternal Haplogroup report is waiting for you,” when it’s very clearly not. The email says the report “includes insights about your DNA,” which it clearly does not, because there is no report. 23andMe knows this. That email says “View Report” twice, with links. It’s not a mistake. It’s a hook, using my own DNA as bait, and I’m the fish.

This tactic is misleading, at best. In my opinion, it’s an unethical and dishonest attempt to manipulate unwary or naïve customers. And truthfully, I’m shocked. I never expected behavior like this from 23andMe. It seems so out-of-character about what I thought I understood about Ann Wojcicki. In this 2015 interview in PLOS Genetics, she said, “I think that for our mission, it’s really important that people trust the company.” What happened?

If I WAS inclined to test another family member, given this deceptive bait and switch sales tactic, I assuredly wouldn’t. Telling me I “have” something only to discover I don’t in an attempt to sell me that same “something” is just not a technique I would have expected 23andMe to embrace.

Come on 23andMe, you are, or were, better than this. ☹

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to 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.

DNA Purchases and Free Transfers

Genealogy Products and Services

Books

Genealogy Research

23andMe Changes: Triangulation Doesn’t Work the Same Way

23andMe made a significant change about the time I was recording my RootsTech presentation about triangulation which provided examples at each vendor. Unfortunately, there was no notification to customers, so most people still aren’t aware.

In the fall and winter of 2020, 23andMe made several changes that resulted in losses to the genealogy community.

At first glance, it looks like this particular change is cosmetic – simply a column heading title change – but there are modifications behind the scenes that negate triangulation at 23andMe. At least in the way triangulation previously worked with the functionality genealogists have long understood to be triangulation at 23andMe.

This article explains the changes, what they mean, and how to work around the issues.

Update

Please note that as of March 12, 2021, some of the changes seem to have reverted, but it’s unclear if all changes have reverted to the original status. It’s virtually impossible to confirm because testers cannot search for “Relatives in Common” by surname. Therefore, proceed by confirming that people who are marked as “Yes” for “DNA Overlap” do in fact triangulate on each overlapping segment using the techniques I’ve described below.

Triangulation

If you need a refresher about what triangulation means, how it works, and why it’s important, I’ve compiled triangulation resources into one article, Triangulation Resources in One Place.

Let’s look at what happened at 23andMe.

Before the Changes

Before the changes, it was possible to quickly determine if you triangulated with two other people on at least one segment by looking at the “Shared DNA” column. Now, it isn’t.

This change has HUGE ramifications.

Unfortunately, it’s easy to simply not notice the change or interpret the column heading change from “Shared DNA” to “DNA Overlap,” as unimportant, but that’s not at all the case.

A “Yes” in this column NO LONGER MEANS triangulation.

This change makes the 23andMe slides of my RootsTech session, DNA Triangulation: What, Why, and How, obsolete.

I’m rewriting that section, step by step, in this article.

Previous Information

Click any slide to enlarge

On slide 24 of my presentation, available here, I talked about clicking on a match, then scrolling down to the “Find Relatives in Common” link. If you click on that link, you see a list of who you and that match both match in common.

In this case, Everett Harold (not his surname) and I both match with my V4 kit, DH and Stacy.

That page, back then, had a column titled ‘Shared DNA.”

At that time, a “Yes” in “Shared DNA” meant that the three people triangulate on at least one segment. That’s not what it means now, and the column header has changed too.

What I said in the presentation was this:

“Looking under the Shared DNA column, the people with a Yes triangulate, and the people with a No, do not.

This means that Everett Harold, me, and DH triangulate. It also means that Everett Harold, Stacy, and I do NOT triangulate.”

Please ignore this and the next slide, #25, too, because the 23andMe page has changed – along with the meaning.

Just put what I said and what you think you know about how triangulation works at 23andMe out of your mind. If you haven’t yet watched my Triangulation session at RootsTech, please just simply skip those two slides (24 and 25) so you don’t confuse yourself with old and now irrelevant information.

We’re starting over here with triangulation at 23andMe.

Current 23andMe Information

Here’s the same 23andMe “Relatives in Common” page, today:

Click to enlarge

You can see that while Stacy was marked “No,” on the previous “Shared DNA” page, the column is now titled “DNA Overlap” and she is now marked “Yes.”

The new infographic says this:

Here’s what this change means:

  • Previously, if someone was marked as “Yes,” it meant that in fact all three people did share a common segment of DNA AND matched each other on at least one segment. That meant they triangulated on at least one segment.
  • Currently, this field only means that they share an overlapping piece of DNA with the tester. It DOES NOT mean that they all 3 match each other on that segment.
  • They may or may not triangulate.

You might be wondering how that’s different. It’s very different and quite important.

Overlap Versus Triangulation

Here’s an example of two people who both match me on chromosome 15 and are marked “Yes” in DNA Overlap. Based on this graphic alone, or that “yes,” you can’t determine if this overlapping segment means triangulation, where the orange and purple person also match each other, or not.

  • BOTH of these people match ME on chromosome 15.
  • If they also match each other on a reasonable portion of chromosome 15 where they both match me, then we all triangulate. A reasonable amount of matching DNA at 23andMe is 6 cM, their match threshold.
  • If those two people do not also match each other on a reasonably sized segment (6 cM) of chromosome 15, then we do not triangulate. This would indicate that one match is from my mother’s side, and one from my father’s side, or that perhaps one is identical by chance. In other words, we do not share a common ancestor on this segment which is the purpose of identifying triangulated segments.

Based on other comparisons which I’ll show you how to perform in a minute – the purple and orange people don’t match each other on this segment. Therefore, this segment is not triangulated between me and the purple and orange people.

Previously, for this match, the “Shared DNA” column was marked “No,” and now the “DNA Overlap” column is marked “Yes.”

The three of us don’t triangulate, and “DNA Overlap” now only means that the three people share some DNA on the same portion of a chromosome with me, NOT that they match each other, which would mean that we triangulate.

It’s a hugely important distinction.

Before, “Yes” meant triangulation and now “Yes” just means an overlap, but NOT necessarily triangulation. You have to figure that out for yourself.

Overlap at 23andMe

An overlap simply means that two people match you on the same portion of DNA.

Someone from your Mom’s side and someone else from your Dad’s side will both match you on a segment of DNA in the same location on a chromosome, shown above.  However, they won’t match each other because one is from your Mom’s side and one is from your Dad’s side. Your Mom’s DNA is different from your Dad’s.

To prove that you all three share a common ancestor, you all three need to match each other on the SAME reasonably sized overlapping chromosome segment.

However, things are even more confusing now at 23and Me.

An Additional Complication

23andMe now indicates that Everett and Stacy have a DNA overlap with me, but the chromosome browser shows NO overlap on any chromosome when I compare both Everett and Stacy to me on my chromosome browser.

How is no overlap even possible when Stacy is listed on the Shared Relatives list with me and Everett, AND 23andMe shows a yes for DNA Overlap?

I eventually found the answer, which makes match analysis much more cumbersome for genealogists. What used to be one step now takes several, not to mention the “yes” answer is now unreliable.

Essentially, all that “Yes” in the DNA Overlap field means is a hint for you to dig further.

Determining 23andMe Triangulation

It appears that the only way to tell if your two matches match each other on the same chromosome as you is to “Select different relatives or friends to compare” at the top of the chromosome browser page.

You’ll see your name plus the two people you were comparing against your DNA in the chromosome browser.

You’ve already seen how they match you on the chromosome browser. What you now need to view is how they match each other.

You can remove yourself, and replace your name with one of your two matches, as shown below.

This will show Everett’s chromosome with Stacy compared to him.

Everett and Stacy do match each other on two smallish segments, but not in the same locations as shown on their match with me.

This is Everett’s match with Stacy (purple).

I match Everett on chromosome 18, but not Stacy.

I match Stacy on chromosome 7, but not Everett.

There is no overlap shown.

Ok, I’m adding myself to Everett’s matches, just to double-check.

Next, we’re looking at Everett’s chromosomes in grey. Stacy is purple and I’m orange.

Overlap Issue

I’ve found the confusing overlap issue, but it only makes the situation worse.

Everett matches both me and Stacy on adjacent and very slightly overlapping portions of chromosome 18. However, the amount of DNA where I match Stacy on chromosome 18 is too small to be considered a match when compared to Stacy directly, meaning it’s less than 6 cM – the smallest 23andMe segment to show as a match. This tiny sliver of overlap only shows when comparing from Everett’s perspective where we can see his match to me and Stacy both on the same chromosome.

A secondary change is that now it appears that 23andMe is showing any small piece of overlapping DNA with a “Yes.” Any segment of DNA smaller than 6 cM, their match threshold, should not be listed as overlapping if we all three don’t match each other on at least 6 cM of DNA.

You can work around the changes 23andMe made, but it has made a one or two-step easy process into a more complicated, cumbersome multi-step procedure involving comparing multiple people to each other separately.

Summary

Previous Now
Column Title Shared DNA DNA Overlap
Triangulation Status Triangulation if “Yes” in the “Shared DNA” column Not an indication of triangulation, even if “Yes” in the “DNA Overlap” column
Triangulation Indicator “Yes” in the “Shared DNA” column None, triangulation not flagged

In summary, for triangulation now at 23andMe:

  • The DNA Overlap status of “yes” DOES NOT indicate triangulation.
  • The DNA Overlap status of “yes” indicates overlap on the same chromosome, not triangulation, meaning all three people do not necessarily match each other.
  • DNA Overlap status of “yes” MAY mean the three people triangulate, but further comparisons are needed.
  • DNA Overlap status of “yes” may refer to overlap smaller than 6 shared cM which is not reflected in individual one-to-one matches.
  • The DNA Overlap status of “yes” may therefore not be technically accurate in terms of genealogical matching and triangulation.
  • A DNA Overlap status of “no” means you do not overlap which means you cannot triangulate.
  • To determine triangulation, meaning if you and two other people all match each other if you share an overlapping segment of DNA on the same chromosome, compare each pair of people one-to-one in the chromosome browser.
  • If you do not find overlapping DNA when comparing three people one-to-one, try the same comparison to the other two people from the perspective of one of the other people in the group, as I did with Everett. This may reveal a small overlapping segment, as illustrated in this article on chromosome 18 when I showed me and Stacy on Everett’s chromosomes.

It’s worth noting here that every segment is different. Triangulation on any individual segment should not be extrapolated to mean triangulation on every common segment, even between the same three people, is valid for all overlapping segments. Evaluate each overlap separately.

This fundamental change makes triangulation at 23andMe much more difficult for the genealogist. Fortunately, there is a work-around.

Please feel free to share this article with anyone who may have tested at 23andMe and is using their tools for genealogical purposes.

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