MyHeritage has some great tools for research and one of them is their triangulation tool. So today
we're going to talk about how to do triangulation with MyHeritage DNA matches. Many people, when they
first get into genetic genealogy, see these matches and they assume then that they must
be related to every single one of those matches. And that is not exactly true. There's videos that
I've done about false matches where you can learn how you can share DNA with somebody but not be a
match to them. In other words you're not actually related to them. However there is a method called
triangulation which not completely but pretty much guarantees that you and the people you triangulate
with share a common ancestor because you each receive that segment of DNA from that common
ancestor. Let's go over what triangulation is. So you understand what we're looking at you start off
with a match person A matches person B. And then we add a third person. And person B might match
person C. So we know that person B matches A and C. And if we do a comparison with person
C. They match person A. Now that is not the end of triangulation because we want to see that all
three of these people match each other on the same segment. Not just share DNA with each other but
share the same segment of DNA. And that is what indicates that they, A, B, and C, are related
through a common ancestor. That might seem simple but sometimes it's a little tricky to do.
So here's another way of looking at it with a triangle is we need to make sure that all
three of them match each other. And you can actually do this with 4, 5, 6, even more people.
The key is all of these people have to match each other on the same segment. So let's take a look
at what we need to do to triangulate matches on MyHeritage. The first step is we want to download
the segment list. There is a way that you can look at some shared matches to see if you triangulate.
But if we want to do this in bulk and try to figure out which all matches we want to look
at closer. We want to download that segment list on MyHeritage. If you're looking at the match list
there's three dots in the upper right hand corner. These are the three dots you want to click on
and it's going to give you three options. The option we want is the middle one which is to
export the shared DNA segment info for all DNA matches. Click on that and it's going to tell
you that hey we're going to be sending you this file. It might take a few minutes. And it may.
I've had it take as long as an hour before I receive this file. So just be patient it will
get to you eventually and we go on to step number two. We want to take this file and we want to sort
it by chromosome by start and by end location. Now this file contains lots of other information.
I've stripped out some of it. So I've taken out the names so that this is anonymized. I've taken
out the snip locations, the RS numbers because that's not really needed. And I simplify the
start and the end columns so that they're showing in millions as opposed to with all the numbers.
I’ve now sorted this in my spreadsheet so you can see that hey this is starting at chromosome
number one early on in the chromosome at 0.8 to 3.5. It tells me how many centimorgans as well
as how many snips. So once I have done that in my spreadsheet I am ready to start looking for
segments. And that is step three we want to find the segments to triangulate. So what we're looking
for is we're looking for at least three people who share a chromosome a start and end location. Now
I start with this because if they all share the same chromosomes start and end location
there's a good chance that they might triangulate. So let's take a look through this list and I'm
going to go to chromosome number 14 and from the start location of 21.6 million to 25.1 million.
It's 8.4 centimorgans I have three people that have that segment so I want to take a look at
that segment. Now you'll notice before and after this list of people there are others that are
also starting at 25.6 or even close to 25.6 and there's others that are ending at 25 near 25.1.
So we're going to hold off on those. We want to start with just those that have the same start
and end location and see if they triangulate. So now we have our list of people we want to go
to the MyHeritage chromosome browser. You can find that by going to the tools section or
just seeing this chromosome browser and we want to explore that. Now with this what we're going to do
is we're going to put in our three matches or more matches. I usually start with you know two or even
three matches and the person that we're comparing it to whose file that was. In this case this is my
grandfather. I use his research in a lot of these examples and we click on the compare. And you'll
notice on this one with these three people. It's compared my grandfather each one of these three
but it's also told us that there are no triangulated segments. Now if we look down
in the chromosome browser we can clearly see on chromosome number 14 that there are segments there
that line up but when MyHeritage was looking at each one of these other people compared to
each other there was not a match there. And so there is probably some DNA that is from my
mother or father or I'm sorry for my grandfather's mother on one side and my grandfather's father
on the other side. So that's why it doesn't triangulate. We can go back and we can grab
another set of matches and this is actually the next little segment down below and these three
people different three people from the first three right though in the same area of chromosome 14
they all do triangulate. It says one triangulated segment. That's great. I found the first set of
people that triangulate all together here. So now that I do have this group of people that
triangulate I can start to add in some of those overlapping segments to see if others triangulate
in that group. What I've done is I have highlighted the three that I already triangulated.
Now these ones that were just above 21.6 to 25.1 they didn't triangulate. So I haven't highlighted
them but the 21.6 to 25.7 they did triangulate. And so I've highlighted them and I've labeled it
as triangulation group A. In this instance and looking here there are hey these four more that
start at 21.6 and end you know 25.9, 26.6, 27.6. And in that same general area. So I want to look
and see if these people triangulate. Now since I know that triangulation group A is these three
people they all triangulate I'm going to add these people in one at a time. Instead of showing you
one at a time I already have added all of them in one at a time and checked and all seven are,
all six, or six, of these triangulate there was one that did not. So now I've expanded my group
to not just have one triangulation but I have multiple triangulations on this. I've
expanded that group to even more people and I can continue to do that with other ones until I see
how extensive this group really is. Now the again going back to what triangulation is it indicates
that all of these people share a common ancestor. So I've created a cluster of people that I can
look at together I can look at their trees. We can copy each other on emails for our common research.
If we have lines we might be able to compare back and identify who that common ancestor is
and if I do that, if I find a common ancestor for this triangulation group that segment then
came from that ancestor which means in the future as I'm searching for other segments of new matches
any segments that fall overlap that segment that triangulate with members of this group
are from that same most recent common ancestor. And that's how we can start to
use triangulation to help us identify unknown matches. And for people who
don't know who their mother or father is such as adoptees if they fit into a triangulation
group where you know let's say where you know where the great-great-grandfather is
well if that triangulation group received that segment from that great-great-grandfather
that adoptee that is also part of that triangulation group has to be related to that
great-great-grandfather. And you have helped them with a piece of their puzzle. Now if you would
like to learn how to use a triangulation tool on another platform then why don't you check out this
video up here. If you want to learn something else about DNA then check out this video down below.