Newsletter
- June 30, 2016
North American edition
Your ancestors were immigrants
Free access to over ONE BILLION records
at Findmypast ENDS JULY 6
Free access to 260m Canadian records at
Ancestry ENDS JULY 3
DNA testing comes of age
Can genetic testing determine your
ethnicity?
The randomness of DNA: good news and bad
news
How to download your results from
Ancestry
The wonders of X-DNA
Why don't my brother's results match
mine?
The beautiful truth
Privacy is important
Hot news!
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Your ancestors were immigrants
North America is a land of immigrants -
even the ancestors of Native Americans were immigrants, albeit tens of
thousands of years ago. Of course, no written records exist of those early
migrations - researchers have made their deductions using DNA evidence and
artefacts that have survived (see this Time
magazine article)
- but we are blessed with some
records of more recent migrations, including passenger records, naturalization
records, and the Ellis Island database.
Free access to over ONE BILLION records
at Findmypast ENDS JULY 6
From now until July 6 you can access
over 1 billion records free at Findmypast.com,
including:
There's no catch - you will be expected to register, but you won't be asked to provide credit card or
bank details. To find out more simply follow this link.
Note:
Findmypast have over 8 billion records in their collection, including the
largest collection of Irish records online. Searching is always free, but to
view records that aren't included in the offer will require the purchase of
credits (or an appropriate subscription).
Free access to 260m Canadian records at
Ancestry.ca ENDS JULY 3
It's Canada Day tomorrow, and until July
3 Ancestry.ca
are offering free access to all 260 million Canadian records - just follow this
link.
DNA testing comes of age
There are now around 3 million people worldwide
who have taken autosomal DNA tests, most of them family historians - whereas
there are less than 2.4 million with current Ancestry subscriptions. I mention
these amazing statistics because many researchers still think that DNA testing
is something to consider for the future. Well, the future is here!
Of course, making sense of DNA matches
isn't easy - but then it can be a great struggle to make sense of online trees,
many of which are unsourced (or, even worse, mistakenly linked to the wrong
sources) and perpetuate errors by making them easy for others to copy.
There's a great TED
talk about DNA that I watched recently. I don't usually watch online videos
but this one is exceptional - so exceptional that I've embedded it in this
newsletter:
DNA
testing is just another way of finding cousins, so don't spend out on a
DNA test until you've tried the free options, such as completing your My Ancestors page at the LostCousins
site.
We're used to there being a trade-off
between time and money, so it's natural to assume that if you spend out a large
sum on a DNA test you're going to be saving yourself time - dream on! You might
think that it's tedious looking up censuses and keying in data, but believe me,
sorting through DNA matches and trying to make sense of them is much harder,
and far more time-consuming. And, of course, it's infinitely more expensive.
So why use DNA at all, if it's more
expensive and more difficult? Because it can tell you things about your ancestry
that conventional research may never discover (because the records don't exist,
or were falsified). Most importantly DNA testing can not only confirm what we
know, and contradict what we think we know, it can also help to knock down
seemingly impregnable 'brick walls'.
Best of all, the evidence is inside us -
we don't have to go hunting for it!
Can genetic testing determine your
ethnicity?
Someone asked me recently which of the
DNA testing companies will provide the most meaningful autosomal results. The
simple answer is - none of them! In isolation DNA results mean very little -
they're just a jumble of letters - but they acquire meaning when they are
compared with results from other people.
Of course, most DNA testing companies
will claim to tell you something about your ethnicity - but as I pointed out
recently, Ancestry reckon my brother's ancestry is 20% Irish, which is virtually
impossible, given how far I've traced back without finding any Irish ancestors
in our tree.
I've uploaded my brother's results to
FamilyTreeDNA - they reckon he's 40% Scandinavian, 40% British Isles (including
Ireland) and 20% Southern Europe; but they tell me that I'm 59% Western &
Central Europe, and 41% Scandinavia. We have the same parents, so how can our
ancestry be so different - of course, the answer is
that it can't!
The truth is,
DNA tests are pretty poor at telling us about our origins hundreds or thousands
of years ago. One of the reasons for this is the simple fact that we haven't
inherited any DNA at all from most of our ancestors!
Note:
some the tests that 23andMe
offer are designed to provide health-related information - these may have some
value on their own.
The randomness of DNA: good news and bad
news
If you test your autosomal DNA you'll
get hundreds or thousands of matches, and naturally you're more likely to get
matches with close cousins than distant ones - since close cousins are more
likely to share large segments of DNA (this page from the ISOGG
website gives the statistics).
However, the fact that you're more
likely to match with close cousins doesn't mean that most of the matches you
make will be with close cousins - in reality the majority of your matches will
be with cousins who are so distantly related that you wouldn't expect to share any significant amount of DNA with them.
How can both of those statements be
true? What you have to remember is that we have many, many more distant cousins
than we do close cousins - according to this article,
calculations by Ancestry DNA found that on average we each have 193,000 living
cousins who are 6th cousins or closer, but that almost of them are 5th (17,300)
or 6th (174,000) cousins. The article doesn't give a figure for the numbers of
7th and 8th cousins, but clearly they're likely to be in the millions.
According to the ISOGG chart I mentioned
earlier, 8th cousins share (on average), just 0.000763% of their DNA, which
equates to just 0.05cM - in other words, it's such a small amount that it would
be dwarfed by the DNA that is shared by chance. So, as you can imagine, I was amazed
when Ancestry claimed to have found a match with an 8th cousin - a connection
that was backed up by our family trees.
What Ancestry don't
provide is any detail of a DNA match - but fortunately my cousin had uploaded
his results to the GEDmatch site, and there we could see that we shared an
amazing 24cM segment of DNA. A segment this length would be more typical of 3rd
cousins than 8th cousins, so you might be wondering how this can happen.
With each generation DNA is diluted by
half, since every child has two parents, each with their own set of ancestors.
If you refer to the ISOGG chart you'll see that 3rd cousins are 7 degrees
apart, and on average their shared DNA amounts to 1/128th (1 divided by 2 to
the power of 7). Similarly 8th cousins are 17 degrees apart, so on average their
shared DNA amounts to 1/131072 (1 divided by 2 to the power of 17).
If I tossed a coin 17 times, on average
it would come up heads 8.5 times - but 1 time in 131072 trials it would come up
heads every time. Those are long odds, but then we each have millions of 8th
cousins, and we each have 22 pairs of autosomes (chromosomes that are inherited
from both parents). So now it doesn't seem quite so surprising that two 8th
cousins share such a large segment of DNA on one of those chromosomes!
Nevertheless, when you find a DNA match
with a very distant cousin, always consider the possibility that you have
another, closer, match on a different line that is yet to be found. Something
else to bear in mind is that in isolated or close-knit communities where few
people married outsiders the gene pool would be smaller, and this would
inevitably make matches appear closer.
Note:
amongst the useful tools at GEDmatch is one that will analyse how closely
-related your parents were before they married - whilst few people knowingly
marry their cousins, there must be many who do so unwittingly.
The fact that DNA can sometimes reach
back further than expected can be good news - but it can also cause confusion
if we don't take the possibility into account when we're trying to work out how
we're connected to our DNA cousins.
How to download your results
from Ancestry
To upload your DNA results to GEDmatch
(or any other site) you must first download them from Ancestry or Family Tree
DNA. This is very easy to do, but if you haven't done it before, this brief
guide for Ancestry users will prove invaluable.
First look for the Settings link at the top right of your DNA home page:
When you click the button you'll be
taken to the Test Settings page -
look for the Download Raw DNA data area
on the right:
When you click the button Ancestry will
ask you to enter your password: they'll then email you a link that will allow
you to download your data. It will be downloaded as a ZIP file, but there's no
need to unzip it, as GEDmatch will only accept the data as a ZIP file. (And, by
the way, you certainly don't need to understand the data!)
Uploading your results to GEDmatch is
easier - simply register or login, then click the AncestryDNA
link under File uploads. You'll need
to know where the file you downloaded from Ancestry has been saved - usually it
will be in the Downloads folder, and the filename will look something like
this:
dna-data-2016-06-10.zip
Some of you may have noticed that whilst
I've written extensively about Y-DNA, autosomal DNA,
and mitochondrial DNA I haven't talked about X-DNA up to now.
I intend to remedy that in this article,
although I'm going to start by reminding you what all these different terms
mean….
The term autosomal DNA refers to the 22 pairs of chromosomes that we inherit
equally from our parents - one chromosome in each pair comes from our mother,
one from our father. We also inherit two more chromosomes - an X chromosome
from our mother and either an X chromosome or a Y chromosome from our father.
These last two are known as the sex chromosomes, because they determine gender
- females inherit two X chromosomes whereas males have one X and one Y.
At first this all sounds quite
straightforward, until you remember that each of our parents inherited 22 pairs
of chromosomes from their parents (our grandparents). If our parents had passed
on all of the DNA they inherited we'd have four sets
of chromosomes, not two (and our children would have eight).
If you didn't already know the answer
then I'm sure you've figured it out by now - the autosomal DNA that our parents
pass down to us is a mixture of their own parents' DNA, but it almost certainly
won't be an equal amount from each grandparent because the process of meiosis (in which the
chromosomes are mixed) is essentially random. This means if you have siblings
they won't have inherited the same mix of your grandparents' DNA as you have -
only identical twins inherit exactly the same DNA.
Mitochondrial
DNA, usually referred to as mtDNA, is passed from a mother to all of her children.
However, because males cannot pass their DNA to their offspring mtDNA tracks the direct female line. Sadly mtDNA is limited value to genealogists because it mutates
so slowly - even if you match someone else exactly, the chances are that your
common ancestor lived upwards of 500 years ago. However it can have probative
value - it was mtDNA that helped to identify King
Richard III
Y-DNA is passed by fathers to their sons - that's why it
usually follows the surname, and why Y-DNA testing is the cornerstone of most
surname studies. Of course, not every male with the same surname has the same
Y-DNA - quite apart from adoption and illegitimacy, which remove the link
between surname and DNA, very few of the surnames which survive today
originated with a single individual.
Now we're ready to address X-DNA. X-DNA is tested as part of an
autosomal DNA test, such as Ancestry
DNA or Family
Finder from Family Tree DNA. Because we have 22 pairs of autosomes but only
one or two X chromosomes we're much less likely to get meaningful matches on
the X chromosome, but when we do it can be a welcome bonus.
If you're female you will have inherited
an X chromosome from each of your parents; if you're male you'll have inherited
only one X chromosome, from your mother. You might think this makes X
chromosome testing more useful for females than for males, but as with so many
aspects of DNA, it ain't that simple! Here's why: if
I get an X-DNA match I know with absolute certainty that the shared ancestry is
on my mother's side of my tree, which makes it a lot easier to figure out who
the common ancestor was.
Actually it's not just my father's
ancestors that can be eliminated - because sons only inherit X-DNA from their
mother's there are many other ancestors who can be excluded from consideration.
I've adapted the Ancestor Chart that so many members find useful, to show which
ancestors provide the X-DNA that a male inherits from his mother:
You can download an A4-sized PDF by
clicking here
(the original chart can be found here). The
boxes which are shaded represent ancestors whose X-DNA hasn't been passed down
to me, and the percentages shown indicate the average amount of X-DNA that each
ancestor has contributed (the actual figure could be very different).
The pattern of inheritance is different
for females - they inherit an X-chromosome from both parents - and whilst I'm
sure you could work it out for yourself, I'll put together another chart in
time for the next newsletter.
Why don't my brother's results match
mine?
If you look at the chart above you'll
see that I inherited 100% of my X-DNA from my mother, and of course my brother did
too. You might expect, therefore, that just as our Y-DNA matches exactly
(because we have the same father), so does our X-DNA.
Autosomal DNA and X-DNA matches are
measured in centiMorgans, usually abbreviated as cM (if you're interested in finding out what a centiMorgan is, this page on the ISOGG website tells
all). Segments which are more than 10cM long generally indicate shared
ancestry; segments below 7cM usually match by chance (unless you and your
prospective cousin also have longer segments that match).
But this page from the free GEDmatch site shows how little of my brother's X-DNA
matches mine: the green sections are where we match, and it's likely that these
are all chance matches apart from the 10.7cM section which is highlighted in
blue.
How can our X-DNA be so different when
we both inherited our X chromosome from our mother?
It's very simple - like all females our
mother had two X chromosomes, one inherited from her father (our maternal
grandfather), and one inherited from her mother (our maternal grandmother).
Clearly one of us has inherited X-DNA that comes mainly or entirely from one
grandparent, whilst the other has inherited X-DNA that comes mainly from the
other grandparent.
Have you ever comes across the Fibonacci
series? This is a mathematical function that pops up time and time again in
nature, and it just so happens that it describes perfectly how many ancestors
from each generation have passed their X-DNA to me.
Here are the first few terms of the
Fibonacci series:
0, 1, 1, 2, 3, 5, 8, 13, 21, 34……..
What you will notice is that each term
in the series is the sum of the two preceding terms, for example 1+1=2, 1+2=3,
2+3=5 and so on. This in itself is interesting (for some of us) but what's
really important for me as a genealogist is the fact that these numbers also
represent the number of ancestors from each generation who have contributed to
my X-DNA.
If you refer to the chart above you'll
see that I have inherited my X-DNA from 1 parent, 2 grandparents, 3
great-grandparents, 5 great-great grandparents, and 8 great-great-great
grandparents - and whilst it's not practical to include more generations on a
single sheet of A4 paper, I can assure you that there would have been 13
ancestors from the next generation (out of 64), 21 (out of 128) from the
generation after that, and 34 of my 6G grandparents (out of 256).
Why might this be important? There are
two reasons - the obvious one is that with fewer ancestral lines to consider
it's usually going to be a lot easier to determine which ancestors we share
with our X-DNA cousins (compared to resolving atDNA
matches).
Less obvious, but equally important, is
that because X-DNA is diluted less with each generation it has the potential to
reach back further. I inherited an average of just 3.125% of my autosomal DNA
from each of my 32 great-great-great grandparents, but between 6.25% and 25% of
my X-DNA from 8 of them.
For this reason you'll often find that
you don't share any meaningful segments of atDNA with
your X-DNA cousins - though when you do, it's a bonus!
Ancestry trees work well for some, but there
are many people who value their privacy, and wouldn't dream of posting personal
information about themselves or their family where everyone can see it. Some of
those people are my cousins, and some of them are your cousins - but how could you
and I hope to connect with them online given their concerns?
It was because of this conundrum that, when
I was inspired to start LostCousins back in 2003, one of my key aims was to design
a site where cousins could meet without the privacy of either party being
compromised. I'm glad to say to say that it has worked amazingly well - nobody
has ever complained that their privacy has been breached.
Hot news!
This is where any last minute updates
and corrections will be highlighted - if you think you've spotted an error
(sadly I'm not infallible), reload the newsletter then check here before
writing to me, in case someone else has beaten you to it......
That's all for this issue - I'll be back
soon with more news from the wonderful world of genealogy.
Peter Calver
Founder, LostCousins
© Copyright 2016 Peter Calver
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