graphs they're not always going to line up and so it's
there's not as much data that has been tested between them
ways. GEDmatch has a way that you actually see all that data
particularly when you're doing visual phasing. If you have any
if you like this video, be sure to give it a thumbs up and
question about the scales we use in measuring DNA, you can
at one time. It's important to remember because they have
snips, and sentiments and there can be visualized in different
areas that are not lining up exactly how you would expect
it's also with colors not being the same because some of those
points they don't line up near as much and that's because
together if you're using different companies kits that
recombination points are so there's a couple of ways that
we're lining them up. Not everything is going to line up
looking at whenever you are looking at segment data
always the way that we want and so be sure you know what you're
important that we go in and we take a look at the actual
segments end those are the scales that we use, megabases,
don't have as much overlap you may miss where those
represented in both of them. But on the living DNA, besides
put it in the comments below and I'll try to answer it and
up as a match even though it may not be and that's just one
different bases as to how those measurements are made when
it's also still a shorter distance and so there's much
DNA but they were tested on the others now where this can be
amount of this is green between these areas whereas when I look
almost all of it is green and even on the first one a sizable
location the megabases of where segments start and where
and so whenever I'm doing visual phasing and lining up my
snips were not tested in common now we of these snips not being
down on the living DNA one you'll notice it's really only
less snips in this area than what I see in the other. One
about half and half between green and yellow so there's a
there are a few other tick marks that are also red but I
the fact that this living DNA has already been stretched out,
marks. This is the first tick mark after that 30 million. So,
notice is between the first two, they're about the same
lined up and it looks like it's about lined up with what we see
first little batch of you know, lots of green that's almost
problem is if you had a small segment in visual phasing where
let me look the right hand side just a bit. Again, we have this
this represents itself is it represents itself then with
lot of those similar snips that were not tested on the living
tested in common again you can see as I go to these other data
there was actually two recombinations really close
might even begin to think well this may be a match and if you
thing that I can show is that on the second one there's
don't see any of those in the living DNA and that's because
that are immediately next to that 30 million, you'll notice
immediate to the left of it. We have those red segments right
starting point is at 30 million. If I go back to the
tick marks there, one, two, there, one, 2 there. So, this
next tick mark and the next tick mark, there's one, two
that hey here is where that segment is starting. Just
up as best if I could and what we can see here is we can see
to look at more people as far as where of those recombination
points are. So let me show you how this can be even more
length as far as the number of snips that are being
mark. This is going to be 32 million. One thing you will
some of these get a little bit harder to see because of the
lack of overlap on these snips. So let me go to the next tick
DNA kit. Now the Living DNA kit shares much less snips with the
there, right there, and right there. Now this is it's
confused when we add another version of these same two
this is represents 31 million and those all are within that
little area right there. Now, as I go a little bit further,
in the living DNA and I can do that by checking out my tick
of the size of these other two in relation. But I've lined it
kit. So I wouldn't expect to see as much information and you
that yeah this starting place is right about the same and to
necessarily exactly in line with what we would think
enough that you may get confused when you're starting
they're maybe offset a little bit not by too much but just
not shared in common with me and my father now as we're
go over we can see that there's some parts that they're
of those now first I've tried to line up the megabases for
actually put the threshold low enough then it's going to show
of the importances of looking at the amount of overlap so now
show up as not matching now if you are looking at this you
with an ancestry version two kit now again these both use a
and we can start to see where common recombination points are
Visual phasing the idea is is that we line up these graphics
those snips are not ones that overlap and so they couldn't
Understanding these different scales of how we measure DNA is
people with a different kit. So I've brought up now the Living
starting to line up it looks like but they're not
lower one but those red tick marks indicate that segment is
the left of it there are some red tick marks although there's
important to start looking at some of the scales. So, this
is between 28 million and 30 million. Besides the red marks
that on the 23 and me version three and on the ancestry,
the centimorgans for it however remember I said that
there's really no good way to show how much sentimorgans
as far as how much length all throughout the human genome,
it would be great if we had a third line on there that have
each one of these into about the same spot and we can see
places there's fewer snips per megabase that's why you're
in some places there's more snips per megabase and in other
can see that just from the distortion of it. This actually
when I imported this file, this graphic was only about a third
going along the DNA and just going from left to right as we
ancestry or the twenty3 and me version three or version four
a lot more red tick marks on the upper one as opposed to the
differences between them let me go through and highlight some
I'm looking at my grandfather and me and I'm looking at it
with one of them from a 23 and me version 3kit and one of them
problem where things don't line up exactly so for instance here
less than one centimorgan for every megabase over that
alongside the snips and the mega bases when we're doing
instance, if I'm looking at the second segment on here 241
megabases to 164 megabases. So, about 130 megabases long and
sentimorgans is based on ability and because it varies
segment and so you can see that even just on this chromosome
between siblings but sometimes we may run into a little
different set of snips and so we're going to see some
really important when we're looking at visual phasing.
varies from below one to two or more sentimorgans per megabase.
number one, the amount of sentimorgans per megabase
seeing the variation in the size of the gap between any two
there's a hundred and 9 centimorgans. There is actually
megabases to 249 megabase. It's about seven and a half
every megabase in that segment. On the other hand, if I look at
megabases long and I can see that it is about 15. 4
the very first segment, I see that it's going from about 30
centimorgans. So, there are about two centimorgans for
tell you how much sentimorgans is in that segment. So, for
that graphic but if you are looking at the table, it will
of those carrots now finally we have the centimorgan scale now
again that's because the graphic is sized based on the
count 10 of those carrot marks. So, this is a when you're
position something is in what you can also see is that the
and each one of those carrot marks represent one megabase.
that the scale for absolute length was megabases. How are
representation length of the chromosome. Now, I told you
So, don't get confused when you're looking at the full
resolution that the snip scale which is each one of those
pixels and it's what the actual length of this graphic is, is
chromosome number twenty-two should be the shortest one.
seven. Now, chromosome number one is showing that it's
and two in this case were actually reduced by half and
we're looking at full resolution you'd actually think
megabases. So chromosome number one is the longest chromosome
number twenty-two is the shortest. So normally when
chromosomes from one to 22 are ordered by the number of
represent 200 snips, but it's still snip scale. Our
means is this was so large that they actually had to go and
However, you'll notice that there is an image size
chromosomes they can represent all of the snips represented
and there's some of them that are longer like this one and
actual length between any two of these marks is a little bit
different there's some of these that are shorter like this one
of the length of the chromosome is. So then, what is the
number of snips but this bottom scale is the megabases and so
actually zooming in you can see roughly what position absolute
tick mark and those are all at even intervals all along this
you look really carefully you can see that there is a little
megabases and underneath that, there is a little carat mark
So, if you actually go between 30 and 40 megabases, you'll
at the bottom and you can see that it has this K and thirty M
and what this is, is this is position 30 million or thirty
than on chromosome number two. You can also see that
shorter than chromosome number two but really all that means
is there is just fewer snips tested on chromosome number one
that chromosome number one should be the longest one and
case of red we don't share in common at all what's more if
the exception here in just a moment. So each one of these
easiest to see on here because actually it is every single
chromosome number two or one but that's not because the
chromosome number four, five, and seven are even longer than
it's the snips. Don't get that confused with the overall
chromosomes are longer. It's because chromosome number one
reduction one half on some of those chromosomes and what that
each one of those pixels represents a single snip.
without having to scroll too much along the screen and so
divide it in half and so each one of those tick marks
this one I have chromosome one three, four, five, six, and
many snips were tested on each chromosome. So you can see on
some red intermixed in that and that's a black bar underneath
and the parts that we don't match which would where there's
green and it has the blue bar indicating that's a half match
tick mark underneath the black or blue bar just a straight
chromosome they represent about 100 or in some cases 200 snips
bars along here represents a snip that we either share
completely in common or we just share half in common or in the
pixel represents a single snip. Most of the time we'll get to
whenever they test your DNA and as I've explained in other
that checkbox for full resolution is checked. This is
the screen. You're going to have to scroll quite a ways to
between myself and my grandfather and this is on
doing your one-to-one comparison is make sure that
going to make a graphic file that covers a big long area of
showing that we don't match well the snip scale is the
thing for all of us is all of your genetic genealogy websites
chromosome number one and what you see as you can see the
parts where we're matching which would be the yellow and
on a particular segment now the third type of measurement is a
see everything. So, here is a segment of DNA and this is
amount of organs per mega basis varies quite a bit the good
whenever they see a match of how much sentiments they match.
the one-to-one comparison. What you need to do when you're
three of these scales at one time. And you do that by using
familiar with the centimorgans because they have seen that
now this is where the exception comes in is for most of your
the different things? For instance, most people are
mega basis as well and you might have seen how many snips
megabases shown on these graphics? Well, that scale is
If you've gone into segment data, you might have seen the
length of the chromosome. That is not what the representation
chromo numbers four, five, and seven are not reduced by half.
However because we're looking at snips. It all depends on how
where we actually see variety among all of people that have
sentimorgan is related to recombination, it is probably
scales, you might be wondering, well, where can we actually see
megabase but again, along each one of our chromosomes, the
almost two centimorgans per megabase whereas chromosome
in some cases and so this is what you're actually comparing
videos, the amount of overlap between two companies test
scales. A GEDmatch actually has way where you can see all
make up that segment. That on a basic level is those three
between two different locations a snip is a place on the genome
location. Now, the next way that we measure DNA is by
with other people. So, since we have these three different
use about 500, 000 to 700, 000 snips that they're testing
number two, it averages about one centimorgan two one
tested. Each company uses a unique set of snips and they
places along the human genome where that is higher or even
different people's DNA and so it's the one that is used most
average across the entire human genome about 1. 25 centimorgans
varies from anywhere as low as 10% to as much as 90% or more
snip distance and what this is is this is the number of snips
often in genetic genealogy. On average and again, this is just
is equal to one megabase. However, there are lots of
where the letter can actually vary and so that is the place
will automatically calculate how much sentomorgans you share
can be really confusing. However, because this
centimorgan is is it's actually based on a probability of
then it's always going to be the same as far as the megabase
genealogy websites they use Build thirty-seven. And so if
lower. For instance, chromosome number nineteen, it's actually
and because this is a probability the amount of
the most important measurement in order to compare two
we actually measure in most the rest of the scientific world
recombination. Now, that may sound really confusing and for
twenty-eight millionth base pair along that chromosome.
Because we use different standards of the human genome.
down to a number that's really easy to understand. So if you
sentimorgans take up a lot of mega basis and so that's why it
varies along a chromosome. You might have one place where
difficult to understand because it's not a simple location of
sentimorgans are really short and another place where
the most part it is because it's unlike anything else that
sentimorgans or CM. Now, sentimorgans is a lot more
sentimorgans varies from chromosome to chromosome and it
about 3 billion base pairs on each set of chromosomes and so
you make sure that you're always using Build thirty-seven
is megabases and what this is is this is an absolute
you go so many places and that's where you're at. What a
Each build is going to have slightly different numbers for
for the amount of DNA that we have. So, let's go over what
each one of those is and how it might be useful in genetic
different ways that we can describe how much DNA we may
megabase just means a million bases and so it shortens it
share with somebody else. There's different measurements
a particular position. And that's why you want to know
measurement of the position along that chromosome we have
what build you're using. For almost all of the genetic
are looking at position 2-8 megabases then that is the
genealogy. The first is the easiest to understand and that
a chromosome may have hundreds of millions of base pairs. A
upcoming episodes. When we're looking at DNA, there are
segment of DNA. Be sure to subscribe to our channel and ways on one website.
In genetic genealogy, there are several different ways to look
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look at DNA in different ways and how you can see all those
Howdy, I'm Andy Lee with Family History Fanatics and this is a
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at the amount of DNA and today, I'm going to go over how we can