I don't know what human's fascination with twins are but
twins are pretty cool and today, we're going to talk
about twins and DNA.
Howdy, I'm Andy Lee with Family History Fanatics and this is a
segment of DNA. Now, one of our users had a question about
whether or not Identical Twins have the same DNA and the
simple answer to that is yes but with most things,
everything's not so simple. So, let's talk about twins and how
their DNA is the same but also how it could be different. This
video is sponsored by Family Roots Conference. Do you have a
to connect with your family, discover your heritage, or find
out what it is that makes you tick? Then join us on September
28th and 29th of twenty 18 in Saint George, Utah at the Dixie
Convention Center for the We Are Family Family Roots
Conference. There's more than 80 classes, a free youth event,
and lots of activities for the family that you can enjoy
learning about your heritage and also having fun together.
So check out the links in the description below and join us
in St. George Utah on September 28th and 29th. Now, first off,
when we're talking about twins, let's separate out between
identical twins and fraternal twins. Now, fraternal twins
develop when two different eggs are fertilized and so they have
distinct DNA between each other. In fact, one can be male
and one can be female. So, fraternal twins DNA is the same
as any other siblings. They're going to share approximately
50% of it. Now, identical happen when a single egg is
fertilized and that splits and two embryos are developed from
that rather than just one. So because these two embryos came
from a single fertilized egg they each have the exact same
DNA. Initially. Now as these two develop both in the womb
and out of the womb there are some changes that can happen
which actually makes their DNA slightly different. Two things
can happen that can change their DNA. First one is
mutations from radiation or environmental effects that
actually change certain parts of the DNA. Now, if there is
one of the embryos that that is affected by that the other is
not affected by, then, that is going to cause a change in that
DNA of that one embryo. The second thing and probably the
most common thing that can happen is our cells are
dividing all the time and as an embryo is developing, it's
going these divisions. Now, DNA, it's pretty close to
perfect as far as copying itself but pretty close doesn't
mean exactly and so every now and then, a transcription error
gets created in that DNA. Almost all the time, it is in
an area that's not going to affect anything. So, from an
end result of the person, it doesn't matter but what it does
do is over time these add up so that these two embryos are
slightly different in their total DNA makeup. So, how
different are twins really? Studies have shown that they
have about one hundred to one hundred and 50 single letter
differences between their DNA. Now, that may sound like a lot
but if we look at this red bar right here, that represents
three billion letters of our entire genome. 1 50 differences
is represented by that green bar that you can't even see
right there. That's how of a difference 150 is. Another way
to look at it is out of 3 billion, 100 differences would
be one every 30 million letters. That's the odds of
winning the lottery. Now, most DNA genetic tests only look at
about 500, 000 snips. So, in order to find one that is
different between a set of twins, you would actually have
to look at 60 twins to just find one between all of them.
Now, more likely the case is when you ever look at twins,
you're going to find several differences between their DNA
and that is probably because of misreads in the ability of the
processing to read the DNA in the first place. For instance,
out of 500thousand. If you are ninety-nine point nine nine
percent accurate in reading the correct snip, you're still
going to have 50 that you read incorrectly. Now, that's the
same as if you actually compared your DNA between two
testing companies. What you've really done is you've created
two twins. You and yourself. Just a different testing
company that has looked at it. So if we're looking at me here
between 23 and me and Ancestry you can see that there's a
couple of red bars would indicate that we are not a
match in those locations. Well the DNA came from me. And so
those red bars actually represent misreads from one of
the companies in what my DNA was. When we're looking at
matches though and we know that twins are involved, there is a
couple of things to keep in mind. First off, because twins
DNA is going to look identical from a matching standpoint, you
can have uncles and aunts that look exactly like your father
and mother. That can be very confusing particularly when you
don't know how certain relationships all line up but
we can use the same principle to our advantage if your mother
or father has already passed away so they can't give a DNA
sample but they had a twin who's still living. That twins
DNA can be substituted as your father or your mother's DNA
because it's the same. So, if you're a twin, give us a shout
out in the comments below because you're pretty darn