Phasing that almost sounds like a Star Trek laser gun, but when it comes to genetic genealogy,
what is DNA phasing? Howdy, I'm Andy Lee with family history fanatics, and this is a segment
of DNA. Be sure to subscribe to our Channel and click on that bell if you'd like to be notified
about upcoming episodes. We each get two sets of chromosomes, one from our mother and one from our
father. When we do a DNA test, and it's processed, the computer looks at different locations along
our DNA and assigns it to letters one from each chromosome. And that may be AC that may be AT,
or it may be AG. Lining it all up, it looks like all those A's belong on one chromosome and the C,
T, G belong on another chromosome, but the computer doesn't know that, and that may not
be the case. In fact, there's several different combinations just from these three locations that
could be the two different chromosomes. Phasing is the process of taking this information and
dividing it up into the correct chromosomes so that you have this information. In order to do
this, you need to have your mother, or your father tested. Phasing improves the matching abilities
are the different algorithms because it eliminates the times when the computer is actually zigzagging
between the two chromosomes to identify and match. All of our matches can be sorted into our paternal
line or our maternal line, but you need to have had at least one of your parents tested in order
for this to work. 23andMe, MyHeritage, and FamilyTreeDNA will automatically do
the phasing for you if you identify which DNA kit is your parent. And you'll see in their matching
results whether or not that match is from the maternal line or the paternal line. In GEDmatch,
you have to do the phasing yourself, but I'm gonna show you how to do that today. So I've logged in
to GEDmatch, and as I scroll down, I'm going to get to the tools section. And in the tool section,
you'll see there's one of these that is called phasing, and that's the one that I want. Now
on the phasing page, I have to put in some information. You can see I've got to put in
the kit of the child and that's gonna be myself, and then I need to put in the kit of each of my
parents. Now I only need one parent to do it, but the results are more accurate if I have
both parents' kits because then I can cross-check between the two parents to make sure that it has
been faced correctly. So let me go and let me click on myself, and I am right here. And then
I'm going to go, and I'm going to find my dad, who is right here. And I'm going to find my mom,
who was just right above that. Once I'm done, I can just click generate, and GEDmatch is gonna
do all the hard work of separating these out. Now that GEDmatch has created both those files,
what I have is I have two new kits that I can use to compare with other people. You can see
the naming convention to be able to identify what kit it is. First off, it starts with a P which
identifies that it is a phased kit. Then it has the GEDmatch kit number of the child, and finally,
there is an M1 and a P1 indicating the kits that are for the mother or for the father. So in the
kit that ends with M1 that is all of the A's, T's, C's, and G's that belong to my mother. And in the
P1 is all the A's, T's, C's, and G's that belonged to my father. I've separated out that pair of
chromosomes into two separate kits. And so now I can look at matches between those separately.
So let me show you what this looks like using the one-to-many matches. If I put in my kit,
and that's just gonna be the non-face kit, and then I display the results. I'm gonna go down,
and I'm gonna look at the first set of matches beyond my immediate family. So here you can see
these matches, and this is beyond my immediate family. So these would be the people that I would
be most interested in and identifying how they're related to me, but since I don't know whether
they're on my mother's side or my father's side, I don't know where to start looking. If I go back
and change it to just look at my father's kit, then I'll see only my matches from my father's
side, and that's the matches from my father's side. Now what I can do from this is I can be
able to tell them where we could be related because I know at least half of my relatives
aren't going to be who these people are related to. I'm gonna download the top 20 matches for
me. And then what I'm going to do is I'm going to use my face kits to match those up. And what
you can see here is you can see from that top 20 matches which of them are from my father's side,
which I colored in blue, and which of them are from my mother's side, which I've colored in pink.
One thing that you will notice is that some of the amount of centimorgans shared changes because of
that phased kit. And again, as we're going through and we're phasing that kit. We're separating out
those two chromosomes so that we don't have any zigzag going on in matching them up. And so we
would expect for some of our matches, just like you see here, some of the amount of shared DNA
has changed just slightly as we phase that kit. And that more accurate amount of shared DNA is
another clue and how we could be related to our distant relatives. If you have any questions
about phasing your DNA or how you can use that phasing information, put it in the comments below.
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