DNA: Asking other family members to test

So far in this introduction to DNA for genealogy we’ve looked at what autosomal DNA is and how we use it in genealogical research, and we’ve looked at the very important issue of potentially unexpected results and the ethical considerations flowing from that. It was essential to cover the latter two issues before progressing to today’s topic: asking our nearest and dearest if they would be prepared to take a DNA test to help with our research.

A quick review of how we use autosomal DNA for genealogy
As previously discussed, the point of establishing how much of your autosomal DNA you share with a second cousin, fourth cousin, third cousin once removed, etc is not the joy of knowing how much DNA you share with this former stranger.  The point is that by finding someone you match at this estimated level you are being guided to the number of generations you need to go back to find your Most Recent Common Ancestor (MRCA). If the amount of shared autosomal DNA, expressed as ‘centiMorgans’ (cM) suggests you are roughly 3rd cousins, then you would expect to find your MRCA at roughly great great grandparent level.  As mentioned in previous posts, it may be one generation closer or one generation further back, but it will be thereabouts.  Armed with that information, you look at both your family trees to locate the common ancestor.  Then, having found your MRCA, and ensured all research is correct to that point on both trees:

  • you know your tree is correct to that point
  • you know you have a biological link to these ancestors (there are no events which would cause a break in the biological link)
  • should you come across another DNA cousin who matches the two of you, you have a pretty good idea where to look for this new match.

It isn’t always as straightforward as this.  You or your new cousins might not have got as far back as that in your tree building.  As mentioned in my previous post on unexpected results, one of you might have no tree at all, as a result of adoption or unknown paternity.  There are also other issues that might complicate this which I’ll cover in a later post.  But for now, at this introductory level, we’ll stick with a basic scenario with everything going smoothly.  The important point is that, knowing where you and your new cousins share common ancestry, you can start to allocate them to a particular branch of your tree, and work on the basis that other testers who also match the three of you will also link to you on that branch.  Bearing in mind that we each have sixteen great great grandparents and 32 GGG grandparents, this will save you a lot of unneccesary work.

Why would we ask another family member to test?
When we ask a specific, known family member to test, we use their results in the same way: It helps us to sort more distant common matches into specific lines on our own tree.  However, since these are our close family members, and since every one of them will have inherited some DNA from our common ancestors that we didn’t, their test results will extend our ‘reach’.  Exactly how they will do this depends on their precise relationship to us.

Essentially the rule is:

  • Your direct line (parents, grandparents, etc) will produce stronger, better, DNA matches but limiting to an increasingly specific part of your tree with each older generation.
  • Your own siblings will have inherited much of the same DNA as you, but also a lot of different DNA.  Although their results will be of no use at all in guiding you to a specific part of your tree (because you have the same parents, grandparents, etc), the parts of their DNA you didn’t inherit will effectively provide you with more DNA matches.
  • Sibling of previous generations (your mother’s brother, your grandfather’s sister, etc) will combine the benefits of the first two categories, but the results will be a bit weaker than testing your direct line – which of course is often no longer possible.

Let’s look at each type of relationship in more detail.

Sibling
If you have one or more full siblings, you know that all of your DNA and all of their DNA comes from the same two people: your mother and father.  However although like you, your sibling will have received half their DNA from your mother and half from your father, unless you are identical twins they will not have received exactly the same DNA as you did.  (Key point: don’t bother asking your identical twin to test)

I can illustrate all this with reference to my own brother.

In my first post about autosomal DNA we looked at the Shared centiMorgan Project.  Click the image below to see it full size on Blaine T Bettinger’s website.

This shows that the average shared DNA with a full sibling is 2613cM, but it could be anything between 1613 and 3488.  My brother and I share 2616cM.  This is what proves we are full siblings.  What interests me, though, is all the bits of his DNA that I don’t share: they are the reason I asked him to take a test.  Since we are clearly full siblings, anyone who shares DNA with him is also my blood relative even if we haven’t inherited any of the same DNA.  Therefore I can use my brother’s DNA results and the trees of his matches as an extension of my own, to confirm and develop my own tree.  Their Most Recent Common Ancestors are my Most Recent Common Ancestors too.  It’s just that we haven’t inherited the same DNA from those ancestors.

If this is new to you you’ll be surprised at how many people can share a decent amount of DNA with one sibling and none at all with another.  After each other, the top matches for both my brother and me on Ancestry are:
A with whom I share 189cM but my brother shares only 102cM
B with whom I share 144cM but my brother shares 153cM
After them our next highest matches are completely different.
C with whom I share 51cM doesn’t show as a match to my brother.  In fact C is our 4th cousin two times over – we share two sets of 3xG grandparents.
Looking at our matches on MyHeritage, four of my brother’s top ten matches (all of them cM matches in the 50s) do not match me at all.

You can see how my brother’s results give me more information and more clues about my own ancestry.  If you have more than one sibling and they are all happy to take a DNA test to help with your research, so much the better!

*****

While full siblings give you extra ‘horizontal’ reach, every other close family member will help you in a different way: they help narrow down to one part of your tree where you and any DNA cousin you share actually match.  Siblings won’t do this because in terms of your direct lineage, everything is identical.

Parent
There are two advantages to having a parent’s DNA results:

  • First, since we inherit 50% of our DNA from each parent, it follows that we have only 50% of the DNA of each one.  This means that your parents’ DNA is closer to previous generations and will include the other 50% that didn’t pass to you.  You might show as a second cousin once removed to a match but your parent will be a full second cousin.  Because of all this, they will have more and better matches, with more shared centiMorgans.  As an example, one of my DNA cousins currently has 321 matches on Ancestry at 4th cousin or closer, whereas her mother has 511.  If her father were also still alive and willing to test, and supposing he had a similar number of matches, that would effectively transform their daughter’s 321 matches into about 1000 better ones.
  • Second, even if only one parent tests this will help you to narrow down any future match by 50%.  If you have your mother’s test results and your new DNA cousin doesn’t match your mother then your shared common ancestors are on your father’s side.  This will help save you a lot of time searching for your connection.

Grandparent
If you’re lucky enough to have a grandparent who is able and willing to take a DNA test for you the same applies as for your parents.  Not only will their results narrow down any matches to a specific quarter of your tree, but their DNA will be even closer to previous generations.  You may match another tester at fourth cousin level, but your grandparent will be a second cousin twice removed – a much stronger and clearer DNA match.

Key point: it always makes sense to test the oldest generation

Aunt or uncle
If you’re able to test a sibling of either parent this will enable you to narrow down any shared matches to one side of your tree or the other, just as your own parent’s test results would.  However, bearing in mind that siblings don’t inherit exactly the same DNA, your aunt or uncle would also extend the reach of your parent’s results horizontally, in the same way that your own sibling would for you.

Your aunt or uncle who is the half-sibling of your parent
This will have the same effect as a grandparent.  Since only one of your grandparents is the parent of your half-aunt or half-uncle, anyone matching the two of you has to be from that specific grandparent’s line.  However, for reasons outlined above, if you had the option to test your half-aunt/uncle or the actual grandparent who is that person’s parent, you should choose the grandparent.  This would provide the same information to help you narrow down matches to a specific quarter of your tree, but their match would be closer to past generations and therefore better.

Half sibling 
Your own half sibling’s test results will help in the same way as your shared parent’s results.  They will help you to narrow down a match to either your maternal or your paternal line.  However, for reasons outlined above, if a parent is still available and willing to test, their results will be better for you.

Cousin
Your cousin, being the child of your parent’s full sibling, will help you to narrow down shared matches to one side of your tree. On the one hand, your own parent will give you better information.  On the other hand, since your cousin’s parent’s DNA will not be identical to your own parent’s, they might extend your reach horizontally on this line, just as your own sibling would.  Even better, though, to test your actual aunt or uncle.

Slightly more distant relations, e.g. second cousin
In reality, unless you have a very close extended family, you are unlikely to pay for your second cousin to take a DNA test.  However, they might have tested of their own volition, and in the absence of any of the above family members, a second cousin’s results can be very helpful in narrowing a match down to a specific quarter of your tree.  You and they are the great grandchildren of the same couple, therefore any other tester who matches the two of you will probably be further back along that same line. 

Key point: Your own son or daughter’s test results will not help you
Your own child’s test results will not add anything to your DNA research, since they have inherited only 50% of your DNA and are obviously one generation further removed from all your ancestors.  On the other hand if they are interested in their ancestry, your own test results will help them to narrow down to one or other side of their tree, just as your own parents would help you.

*****

If all this was new to you I hope, by now, you have a basic understanding of how DNA testing can enhance your family research.  If you’re interested in taking a test, my next post will provide an overview of the five main testing companies.  After that, there will be more to say, but we’ll take a break from DNA for a while.

*****

Edited August 2020
My posts about DNA are aimed at complete beginners and aim to provide information in manageable chunks, each post building on previous ones. Click [here] to read all of them in order, or to dip in and out as you wish. You’ll also find lots of resources and useful links

Using DNA testing to develop your family research

Last September I wrote about deep ancestral DNA testing using Y-chromosomal and mitochondrial tests.  I said back then that I would write more about my experience of using DNA testing alongside traditional documentary research to develop my family tree.

Today I’m going to introduce the topic of autosomal DNA, including inheritance patterns and an overview of how we can use autosomal DNA testing in our family research.  The following four posts will look at:

  • unexpected results;
  • ethical issues, particularly flowing from unexpected results;
  • the benefits of asking certain other close family members to test for you;
  • different testing companies.

There’s a lot to say and if this is new to you it will seem complicated – it certainly did for me when I first started.  I found the best way to learn was to read to understand the basics, and then just do it!  So I’ll do my best to introduce it all in small chunks.  And alongside my own discussion of the topic, and my own experiences, I’ll offer links to websites, books and other resources. There are several online groups, including on Facebook, where you can ask questions if you’re stuck, and people are helpful.  After the initial introduction of some key points over the next few posts I’ll move back to other family history topics, interspersing with more DNA posts from time to time.  I do appreciate that this won’t interest everyone, but it’s a growing and important part of genealogical research these days.

Autosomal DNA
The DNA tests we see advertised for genealogists use a different type of DNA from the two types I wrote about in that previous post.  What they test is autosomal DNA (atDNA).  This comprises the twenty-two pairs of non-sex chromosomes within the nucleus of every cell.  There is also an additional pair of chromosomes within the nucleus, which are the sex chromosomes.  Females inherit one X chromosome from their mother and one from their father.  Males inherit just the one X chromosome from their mother and the Y chromosome from their father.  As we have seen, the Y chromosomal DNA requires a completely different test.  However, some atDNA tests do include testing of the X chromosome, and this can give additional information to help us to understand which of our lines to focus on when we have a match, but for now I’m focusing on the non-sex, autosomal chromosomes.

Building on what we covered in my previous DNA post, autosomal DNA differs from mitochondrial and Y-chromosomal DNA in the following ways:

  • Mitochondrial DNA is inherited by all babies from their mother but only her daughters pass it on.  Boys, therefore, receive this DNA but do not pass it on to their children.  Y-chromosomal DNA is passed on from the father only to his sons.  Daughters do not receive it at all.  By comparison, atDNA is passed on to every child.  There are no differences whatsoever based on the child’s sex.
  • Mitochondrial and Y-chromosomal DNA mutate (change) very, very slowly.  They are passed on largely unchanged.  This means that our mitochondrial DNA (and for males, Y DNA) can connect us to specific ancestors and their kin who lived many thousands of years ago, perhaps in the Middle East, perhaps in Africa.  By contrast, the atDNA changes with every successive generation.  I’ll say more about this below, since this is at the heart of how we use it in our genealogy research, but for now, just note it as a contrasting feature with these two other DNA types.
  • The operation of mitochondrial and Y-chromosomal DNA, passing largely unchanged from parent to child, means that when we follow it backwards we follow just one line: your mitochondrial DNA has passed to you from your mother, to her from her mother, to her from her mother, and so on, back through time.  The Y DNA has worked in the same way, from father to male child, right back through time.  Those types of DNA, then, can take us on a journey up a very narrow and specific part of our family tree: your mother, your maternal grandmother, just one of your 8 great grandparents, just one of your 16 great grandparents, just one of your 32 GGG grandparents, and so on.  (And the same for Y DNA for male inheritance.)  By contrast, autosomal testing provides a 360-degree coverage of all your atDNA inherited from all of your lines.  There is no difference for children of different sexes.
  • Experts tell us that at the present time atDNA testing is accurate only for five or so generations.  I have found connections further back than that which fit with the smaller amount of DNA and with my documented family tree, and that’s good enough for my purposes, but the experts say five generations or so.

Autosomal DNA inheritance
I said above that our autosomal DNA comprises twenty-two pairs of chromosomes.  One chromosome from each pair is inherited from our mother, the other from our father.  This means that we get half our autosomal DNA from our mother and half from our father.  Obviously, each of our parents also inherits half of their autosomal DNA from their mother and the other half from their father, and so on, back through time.

This might suggest that the inheritance of atDNA is very tidy, with progressively smaller, exact fractions from each of our ancestors: half from each parent, a quarter from each grandparent, an eighth from each great grandparent and so on.  But that is not the case.  The atDNA we receive from each parent will not be an exact 50-50% split of what they received from each of their parents.  On the other hand it isn’t entirely random either: there are parameters.

When we talk about amounts of atDNA we don’t usually refer to it in percentages.  There is a unit of measurement: the centiMorgan (cM).  One of the authorities on DNA testing for genetic genealogy is Blaine T. Bettinger.  Since around 2015 he has been investigating these parameters for centiMorgan inheritance through a research project known as the Shared CentiMorgan Project. It is the go-to document for calculating likely relationships based on DNA.  As I write this, his published results (Version 4) are up to date as of March 2020.  Click the following chart to see it full screen on Blaine’s own website.

These findings are based on submissions from almost 60,000 people who have tested their own autosomal DNA and have known and documented relationships with other testers who share some of their DNA.  Locate yourself at SELF on the chart, and from there look around the wide range of relationships with whom you might share atDNA.  You’ll see, for example, that the average amount of atDNA you share with a parent is 3483cM, but based on real test results from these 60,000 participants it could be as low as 2376 or as high as 3720cM.  The average you’ll share with a full sibling is 2613cM but it could be as low as 1613 and as high as 3488cM.  The average shared DNA with a great grandparent will be 887cM but it could be as low as 485 or as high as 1486cM.  Looking further afield, the average amount shared with your 4th cousin is 35cM but it could be as low as zero or as high as 139cM.

How can we use this information to develop our family trees?
By now you may be thinking:

  • ‘Why on earth would I want to know how much DNA I share with a 4th cousin?’
  • Or ‘My great grandparents are long dead.  I couldn’t access their DNA even if I wanted to.’
  • Or even ‘Yes, very nice.  And this has what, exactly, to do with developing my family tree?’

When we take a DNA for genealogy test and agree for the results to be included in a pool of testers we will be able to see which of the other testers share DNA with us.  Depending on which testing company you use, you will be told the name (or pseudonym) of your match; the amount of shared DNA in centiMorgans; the likely relationship you have with that person (based on the amount of shared cM); and you may possibly have information regarding the exact shared segments plus access to the other person’s tree.  You will also be able to see other testers who match both yourself and that other person.  The results are never displayed in a way that enables another person to see private information about your DNA, simply that you match with them at specific segments.

If my atDNA and another person’s atDNA is exactly the same at one or more places (segments) throughout the twenty-two chromosomes, then that means we have both inherited that part of our DNA from common ancestors.  The higher the amount of DNA we share (the centiMorgans), the closer our relationship is.  If, based on the shared cM, our suggested relationship is around 4th cousin, then we will be looking for a Most Recent Common Ancestor (MRCA) at around 3xG grandparent level.  We now shift to looking at our trees.  Assuming we have both done accurate research, if we both have the same ancestor named as 3xG grandparent (or thereabouts, e.g. it could be my 3xG grandparent and the other person’s 4xG grandparent) then we have found our match.  Based on this we now have the following:

  • a further piece of evidence that our documentary research is correct;
  • proof that there were no adoptions or unexpected paternity events along the way;
  • a new cousin who shares our interest in family history and DNA.  From here on, if you’re minded to, you might be able to share research and new discoveries (I have become great friends with some of my ‘new’ cousins, while for others the connection has been more focused and businesslike);
  • and something else that I think is rather wonderful: you now know that this little piece of you has come down through several generations, unchanged, from an ancestor whose name you have and whose life you have been researching.

Of course, it doesn’t always go as smoothly as that.  Your match might not have a tree – I have often taken what little information they have and worked their tree back to find our shared ancestor: the MRCA.  Your match might not even know who their parents are: I have now used DNA to help one person find their biological father and another to find a missing grandfather.  On the other hand, it may be that your match’s tree is more advanced than yours, and that this DNA connection will help you break through a brick wall and take your tree back a generation or two further.  But we can’t do any of this without other testers: our distant cousins living now, who have also tested and whose test results combined with our own are the key to unlocking information about our shared ancestral lines.

Find out more
Blaine’s excellent book, The Family Tree Guide to DNA Testing and Genetic Genealogy was my starting point in getting to grips with how this all worked.
You can read more about the Shared cM Project [here]
And download a PDF with (a LOT!) more information [here]
His website is perhaps of more use if you’re already familiar with DNA for genealogy and are looking for more information about specifics.
His YouTube channel is [here]

Edited August 2020
My posts about DNA are aimed at complete beginners and aim to provide information in manageable chunks, each post building on previous ones.  Click [here] to read all of them in order, or to dip in and out as you wish.  You’ll also find lots of resources and useful links

Traditional Irish naming patterns

With a nod to St Patrick’s Day, here’s a little something for those of you with ancestral lines going back to Ireland (and maybe Scotland too).

One of the difficulties for family researchers with Irish lines is that prior to around 1840 Irish life events are not well-documented.  Of my six direct ancestors who were born in Ireland, English records tell me that one was from County Mayo, one from Belfast and two were, at least at the time of their daughter’s birth, in either Derry or Newry.  For the other two I have only ‘Ireland’.  I have fathers’ names (from English marriage certificates) for only two.

So for any of you with Irish ancestry from before about 1850, you’ll know that we have to think laterally and draw upon any clue we possibly can.  One such clue could be the traditional naming pattern, which was widely used in Ireland across all sections of the community until the late 19th century.

It goes like this:
1st son named after paternal grandfather (patGF)
2nd son named after maternal grandfather (matGF)
3rd son named after father (F)
4th son named after father’s eldest brother (patB)
5th son named after mother’s eldest brother (matB)

For girls the same system applied, but it was not always followed as rigorously:
1st daughter named after maternal grandmother (matGM)
2nd daughter named after paternal grandmother (patGM)
3rd daughter named after mother (M)
4th daughter named after mother’s eldest sister (matS)
5th daughter named after father’s eldest sister (patS)

For both girls and boys, sometimes the order in which grandparents were honoured could be switched, i.e. maternal first or paternal first.

I learned about this tradition only a year or so ago.  Recently I’ve read (in online comments) that it applies to Scottish ancestors too.  I don’t have Scottish ancestry so can’t put it to the test, but if you do you could try it out for yourself.

I decided to try it with my Mayo family.  This is all I know for sure:

  • I believe Margaret and John came to England separately.
  • They married in England in 1857. John’s father was Patrick; Margaret’s father was James.
  • The 1911 census indicates Margaret was from Mayo.
  • John died before the 1911 census. Earlier censuses give only Ireland as his place of birth.  However, DNA matches indicate that he too was from Mayo.  Using them I have narrowed his birthplace to a specific area of the county, but I don’t have a baptism, and therefore no mother’s name.
  • Using this information, I have found a baptism record for Margaret in Aghagower. This is supported by a DNA match in the same township, probably at the generation before.  If it is correct then I have the mother’s name: Honour.
  • This is the only Margaret born to a James with that surname in the whole of Mayo and within a likely time period (Margaret was not sure of her age) showing in all records. However, another group of researchers have claimed this family for their own, and one of us is wrong.  We always have to bear in mind in situations like this that the records we see are not necessarily a complete set.

I’ve looked at Margaret and John’s children’s names, and also the names given by two of their children to the following generation.  All children of both generations were born in England but within a strong Irish migrant community.  I’ve included the date of marriage of each couple, since it’s said that by the end of the 19th century this tradition was dying out in favour of fashionable names.  It’s also said that the tradition was never applied as strongly in relation to the naming of daughters as for the naming of sons.

The detail of the tables that follow will be of no interest at all to any of you.  Instead, just focus on the highlighted boxes.  Where a child is named as expected I have coloured the square peach.  If the expected naming order of two consecutive births is reversed but the expected names were still used, I have also highlighted this peach.

John and Margaret (Irish, now living in England).  Married 1857
Table analysing use of traditional Irish naming pattern in naming of children

Patrick and Margaret (Both of Irish descent).  Married 1880
Table analysing use of traditional Irish naming pattern in naming of childrenWith only two slight deviations Patrick and Margaret did it by the book: their first son died before a second was born.  They therefore re-used the paternal grandfather’s name for their second son.  They also reversed the expected order of father and maternal grandfather.

Bridget and George (Bridget of Irish descent).  Married 1885
Table analysing use of traditional Irish naming pattern in naming of children

Bridget and George named their three sons in exactly the expected order.  Regarding their daughters, the first two were named after grandmothers.  The third, instead of being named for the mother, was named to honour the father’s grandmother who had recently died.  The fourth daughter was then named for the mother, so this was only a slight deviation.  The final two daughters were named Martha and Winifred.  Following the traditional system, Bridget’s eldest sister was Mary.  This name however had already been used (paternal grandmother) and so Winifred was named after Bridget’s only remaining sister.

This leaves only the name Martha which cannot be accounted for.  However, since Bridget has stuck so closely to the traditional pattern, it’s reasonable to assume that Martha is an important name somewhere in the Irish lines.  In other words it’s something to look out for if I were ever to find records of possible families for John and Margaret back in ireland.

How might we be able to use this information?

I can think of three ways.

First, it’s nice to know who our grandparents and other relatives were named after.  Of Bridget and George’s children, for example, I knew Annabella and John.  Knowing that John was named after his grandfather, and realising that Annabella (who was known as Bella in the family) was named after her own great grandmother somehow brings me closer to those people whose lives I’m researching but who died long before my birth.

Second, it gives us a little more information about our ancestors’ lives and what was important to them.  This was clearly an important tradition, and perhaps all the more important for second generation migrants because it connected them back to their lost homeland.

The third way of using this information involves a bit of lateral thinking…
Moving back to my GG grandparents Margaret and John, because of gaps in my own knowledge/ the records, I’ve only been able to accept one of their children’s names as following the expected pattern: Patrick John was named after his paternal grandfather and his father. What we can plainly see, however, is that they passed on an understanding of the naming traditions to their own children.  Surely, then, they would have used it themselves?  (Alternatively, might Patrick and Bridget have followed it more closely than their own parents did because they wanted to honour the traditions of their ancestral land?)

It’s the daughters’ names that can’t be verified.  As explained above, I have Honour as a possible mother for Margaret, and yet Honour doesn’t feature at all amongst the four daughters.  Perhaps the baptism record I have is incorrect?  Or might Honour have been known in the family by her confirmation name to distinguish her from another Honour?  What all of the above does suggest is that it’s worth my while looking for the following names in any possible records that might come to light:
Girls: Margaret, Mary, Bridget, Winifred, Mary
Boys: Patrick, John, James

Using DNA matching I now know that while John and Margaret came to England at the time of the Great Hunger (the famine), most of their cousins emigrated to Pennsylvania.  Bearing that in mind, and armed with the naming tradition information and the above names that are important for my Mayo family, one online family tree really interests me:

John and Maria Padden, contemporaries of my own GG grandfather John Padden, Married in Crossmolina, Mayo, in 1860 before emigrating to Pennsylvania.  This is how they named their children.
Table analysing use of traditional Irish naming pattern in naming of children

Could this John be my GG grandfather’s cousin, or perhaps second cousin?

John and Maria definitely followed the naming pattern tradition.  Most of the important names – grandparents and mother – are accounted for.  Only the father’s name is not passed on.  Instead, the first son is named Patrick.  After the three important women’s names are passed on, three others that cannot be accounted for are used: Margaret, Martha and Winifred.  The overlap with names given to my own family is striking.  This is almost the same family living in parallel across The Pond!

Clearly, none of this gives any conclusive proof.  The idea is merely, in the absence of records, to look for pointers suggesting family connections – leads that might add a little further weight should a possible baptism record eventually come to light.  And DNA matching shows that this family is definitely related to me.

I hope some of this has been useful to you.  If you have Irish or Scottish ancestry and hadn’t heard of the naming tradition, why not give it a go and see if there are any conclusions to be drawn from what you find?

*****

Finally, I hope that all of you and your families are keeping well, and coping with self-isolation and all that involves.