today is another fact or fiction and this has to do with your results that you're getting
from your DNA. So let's get started. Here's the question of the day or the statement really:
the results of Ancestry DNA tests are 99.9% accurate and never changing. Now this statement
has a couple of things in it. First off we have the 99.9% accurate and we have the never changing.
So we need to look at those 2 separately because there are 2 separate and distinct statements.
Now the other thing is what we actually mean by our Ancestry DNA results. There's 3 things that
I think you can mean. There is the raw data there is the matches that you have. And then there is
the ethnicity results or the heritage results. So we need to look at those 3 separately. So we have
2 things in the statement that have 3 things relating to it. So there's actually
6 things. That's not 6 that's 10. 6 things that we need to be looking at. Let's go and see.
Howdy welcome to Family History Fanatics where we love helping you climb your family tree
and have fun along the way. If you're new to genetic genealogy chances are you have tons of
questions be sure to check out the link in the description below for our free guide to the 5
most common DNA questions that we have answers. To starting off with the 99.9% accuracy I guess what
we mean by that is that we get the correct result. So when we're talking about raw data, I've already
done some videos and shown you some analysis where there are 2 problems that can happen with
our raw data. 1 is we can have a no call. In other words the companies as they're analyzing that DNA
trying to determine what letters it is they can't determine that for whatever reason there might be
some contamination. There might be other things and these are usually
minimized by analyzing it multiple times. 2 times, 4 times, 10 times, 30 times,
and taking whatever the maximum number of results are. So for instance if you are going to plan on
analyzing something 4 times yeah 1 time you might have some contamination on it but the other 3
times you probably aren't. And so you'd actually look at what those other 3 results are to find out
what the letters are going to be. The other way that your raw data can be wrong is a missed call
for whatever reason. Again as you're analyzing that data you actually call
it as a different letter than what it is. Now the way that you actually can see this is if
you've tested with multiple companies and looking at particular snips where let's say
3 companies call it an AT and 1 company calls it an AA. My assumption there is is that 1 company
that called it an AA is going to be incorrect. And it's really the consensus of the others an AT.
Now altogether these errors constitute about 1% of what you are given in your raw data meaning
99% of what you have is accurate. So is it 99.9% accurate? no. It's about 99% accurate which is
still really really good. So that's with our raw data. Now let's look at our matches. Well we have
some things that could be errors but at the same time not. Now remember with matches we need to
be looking at whether they match on our paternal side or whether they match on our maternal side.
Some people match on both but the vast majority of our matches are on 1 or the other. Unfortunately
without having 1 or both of your parents DNA you're not going to actually be able to separate
out the DNA into what is from the paternal side and what is from the maternal side. So sometimes
some of our matches are actually zigzagging back and forth between those 2. And they show
up as they match. Now are you going to count this as an inaccuracy. You could accept that.
It's just looking at the data that it has available. So I'm on the fence I'm going
to call that inaccuracy but in general what we do know is that the smaller the segments
the more likely something like that is going to happen. So for instance if we're looking at
you know 7 centimorgans then something like that is going to happen a whole lot more often
than if we're looking at 40, 50, or 60 centimorgan segment. In fact at that rate I think above about
25, 30 centimorgans. From what I've done in some other videos you don't find any of your matches
that are false matches between your 2 parents. The other issue with this part is, with our matches,
the vast majority of your matches are into these really small segments. 10 centimorgans or less.
So for instance on Ancestry I have about 30,000 matches but upwards of 25,000 of them I don't
have it dated right. In front of me upwards of 25,000 maybe even as much as 28,000 of them
are 10 centimorgans or less. So if even just a minor fraction of those
28,000 are these false match types which it's not a minor fraction. It's actually you know pretty
large. Then it's not truly accurate. So with your matches I wouldn't say that they're 99.9%
accurate but when I think you're looking at your more closely related matches let's say
anything that is 30 centimorgans or more yeah. I would say that they're 99.9% accurate for
that. And then we get to the ethnicity results. Let's just say you've seen from other videos.
No there's nowhere close to 99.9% accuracy. It's just not possible because we don't have the data.
So that's your your 3 for the 99.9% accuracy with the raw data. It's about 99% with the match data.
If we're looking at 30 centimorgans or greater yeah it's about 99.9% but if we're looking at
ethnicity. No. It's nowhere. It's not even nowhere close. It's not even there. There's nowhere
there's no real way to actually measure it. So what about the never changing. Well yes. With your
raw data your raw data is not going to change. I mean the only way it's going to change is if they
re-analyze your data if you take another test. So you're not going to see a change in your raw
data. If you download a raw data file today and you download that raw data file 10 years from now
when you compare them it should be the exact same. The matches are determined by those segments.
Now each company is always taking a look at their algorithm as far as how they are determining
what a match is. What they're including in what they're not including in. And so in that case I
think you're going to see some change over time. I don't think that it's going to be never changing.
And this is a good thing because the whole point of looking at this as you gather more data
is to improve that algorithm. In other words 1 of the things that Ancestry did recently was
eliminate a lot of the really small matches. They had and that was a significant number of it.
And they eliminated those basically because the majority of those were false matches.
Well that's improving accuracy if you take out a lot of false matches even if you're taking out
some good matches knowing that most of those matches are false matches. You've actually
improved the overall accuracy of that match list. So your match list is going to change.
Now are you going to see major changes? again on the closely related, no. You're not going to.
And finally with our ethnicity results and this is the one I think that changes probably the most
often. Every year or 2 each company does update and you find that the percentages they give you
are different. In some cases vastly different. Now it's usually not going to go from saying that oh
in this year you were Northwest European. But in the next year that Northwest Europeans all
gone and now you're Southeast Asian. It's not going to be that drastic. It may be moving from
hey Northwest European to Central European or from Northwest to Scandinavia or something like that
as they gather more data as they increase the size of their reference databases. So that they
have a better feel for what group might have been in what area based on those reference databases.
Those results are going to change. And that is the 6 different ways the you can have accuracy
and changes in your DNA results. If you'd like to see what I think the best company in 2021 is,
you can look at this video up top here but if you want to see something else about DNA then
check out the video down below. It's gonna be a great recording session with the allergies.