Newsletter – 14th March 2022



Revealed: the truth about the 1931 Census EXCLUSIVE

How the census changed from 1841 to 1921

Last chance to save on old newspapers ENDS TODAY

Ancestry DNA offers ENDING SOON

Introduction to DNA

Masterclass: How to make the most of your DNA test UPDATED

Peter's Tips

Stop Press


The LostCousins newsletter is usually published 2 or 3 times a month. To access the previous issue (dated 11th March) click here; to find earlier articles use the customised Google search between this paragraph and the next (it searches ALL of the newsletters since February 2009, so you don't need to keep copies):



To go to the main LostCousins website click the logo at the top of this newsletter. If you're not already a member, do join - it's FREE, and you'll get an email to alert you whenever there's a new edition of this newsletter available!



Revealed: the truth about the 1931 Census EXCLUSIVE

For years I've been trying to ascertain the truth about how the 1931 England & Wales Census came to be destroyed; some of you may remember me broaching the topic in my 2010 article What DID happen to the 1931 Census?


All family historians know that around 60% of army service files from the Great War were destroyed by enemy action during World War 2, and many know that the bombing of the Exeter Probate Registry led to the loss of many Devon wills and probate records. It's inevitable that when we heard that the 1931 Census was destroyed during WW2 we'd assume that Adolf Hitler was somehow responsible.


But as I pointed out in 2010:


 "The census schedules, enumeration books, and other documents relating to the 1931 Census were kept in an Office of Works furniture store in Hayes, Middlesex. On the evening of Saturday 19th December 1942 the store was gutted by fire, the cause of which was never identified."


Many sources refer to the accidental destruction of the records, but I was sceptical:


"Since there were special fire hydrants in the store, and there was a guard of 6 fire watchers, it seems incredible that the fire could have developed to such disastrous proportions. I don't know whether there was an enquiry at the time, but I wonder whether it may have been significant that it was not only a Saturday night, but also the last Saturday before Christmas? Was there some sort of Christmas celebration going on behind the blackout curtains?"


Until now I've been unable to find any contemporary commentary on the cause of this disaster, but on Friday I discovered a letter in the National Archives which confirmed my suspicions:


© Crown Copyright


So there we have it: "criminal negligence or sabotage". Clearly the loss of the 1931 Census for England & Wales was not the unfortunate accident that we've been led to believe.


Note: this letter, addressed to Mr V P A Derrick of the General Register Office, can be found in RG 20/109. These papers can currently be downloaded free of charge from the National Archives when you follow this link.


It's not just the 1931 Census that was lost – the Enumeration Books for the 1921 Census were also stored at Hayes and perished in the fire. Who were the 6 fire guards whose apparent 'criminal negligence' led to the destruction? That's my next challenge….



How the census changed from 1841 to 1921

When I began researching my family tree I purchased Making Sense of the Census by Edward Higgs. Published by the Public Record Office (as it then was) in 1989, it provided a handy guide to the information collected – and not collected – in the censuses from 1801-1901. (The 2005 revised edition is still available from Amazon)


But much of the key information is available free in a research guide on the National Archives website – you'll find it here.


You might think that after all this time you know all there is to know about the census returns, but I certainly learned some thing new, and I suspect you will too!



Last chance to save on old newspapers ENDS TODAY

Until midnight (London time) today, Monday 14th March, you can save a massive 30% on subscriptions to the British Newspaper Archive. For example, a 12 month subscription comes down to just £56, little more than £1 a week.


If you have a Pro or Ultimate subscription to Findmypast you'll already have access to the nearly 50 million pages in the archive, but newspapers aren't included in lesser subscriptions. And even if you do have a Pro subscription, heavy users of historic newspapers will appreciate the more flexible searching options – for example you can restrict your searches to pages added to the archive after a certain date, so that you don't keep ploughing through the same list of results and can focus on what's new - this is important because the archive is growing by upwards of 4 million pages a year.


This offer isn’t exclusive to LostCousins, but I'd appreciate it if you could click the link below when you make your purchase, as you'll be helping to support the LostCousins project to connect family historians around the world who are researching the same ancestors.


British Newspaper Archive – SAVE 30% UNTIL MIDNIGHT (London time) MONDAY 14TH



Ancestry DNA offers ENDING SOON

The news about Ancestry's latest offers didn’t arrive in my inbox until after the last newsletter was published, so whilst I did add them to the Stop Press for that issue, I suspect many readers won't have noticed.


The St Patrick's Day offers in the US and Australia end just before midnight on Thursday 17th March, so you'll need to be quick; you've got longer to take advantage of the Mother's Day offer in the UK. Please use the relevant link below so that you can support LostCousins when you make your purchase (you may find that you need to log-out from Ancestry, then click the link again): (Australia & New Zealand only) – $89 plus shipping until 17th March – SAVE $40 (US only) – $59 plus shipping until 17th March – SAVE $40 (UK only) – £59 plus shipping – SAVE £20


Of course, Ancestry DNA isn't just for mothers and those with Irish ancestry – anyone can take the test. You don’t need to decide who is going to test when you place your order – only when the test is registered.


Note: to meet privacy requirements all those who test with Ancestry must have an account in their own name, but they can hand over the management of the test to a relative, usually someone who has an Ancestry subscription.



Introduction to DNA

If you don't understand DNA then you're not in the minority – the reality is that very few people truly understand how it works and the implications for family historians.


In many ways using DNA is like driving a modern car – you don't need to know what's under the bonnet, you just need to know what it can do, and how to control it. Indeed, you'll probably find it comforting to know that the less you know about the nuts and bolts of DNA the more successful you're likely to be!


I've been using DNA for the past 10 years, and during the first half of that decade I was devouring DNA blogs, articles, and books in an attempt to achieve more from a small number of matches. It was frustrating, challenging, and ultimately fruitless – I didn't knock down a single 'brick wall'.


Five years ago I re-tested, this time with Ancestry, and within weeks I was getting the results I'd been looking for all along!


Not only were some of my oldest 'brick walls' tumbling down, I was able to validate much of my paper-based research by making use of the matches I had with distant cousins. This was very reassuring because a lot of research had been done the hard way, poring over microfiche and microfilm, and when you're working under those conditions it's very tempting to accept the first plausible baptism or marriage that you find.


To make the best use of my Ancestry matches I had to forget most of what I'd learned during those five frustrating years, and instead focus on making the most of the opportunities that Ancestry provided. It breaks my heart to hear from members who have been reading up on DNA techniques and tools, because I know that it's only going to make it more difficult for them.


When it comes to DNA a little knowledge is a good thing – it only gets dangerous when you step beyond the bounds of my Masterclass….



Masterclass: How to make the most of your DNA test

Note: I've updated this Masterclass since it was last published in March 2021


We all have 'brick walls' in our trees - in some cases because our ancestors were illegitimate, in others because of deficiencies in the records. Fortunately, because our DNA is inherited from our ancestors it's also a record of our ancestry – one that can not only overcome gaps in the archives but also provide us with a way of checking that our research is correct.


Tip: DNA doesn't replace conventional research, it provides a second layer of connections. It's a bit like overlaying a map onto a satellite image – they are different ways of looking at the same thing, and in most cases each will corroborate the other.


You probably don’t have samples of your ancestors' DNA to compare yours against - though it's technically possible to extract DNA from hair or the gum on the back of a used postage stamp, it's not a service that mainstream companies offer. But there are lots of other people who do have samples for comparison – your cousins. They inherited their DNA from their ancestors, and whilst most of their ancestors will be different from yours, any segments of DNA that you share were almost certainly inherited from your common ancestor(s).


Note: anyone who shares some of your ancestors is a cousin of yours, no matter how distant the relationship; in fact, distant cousins are particularly useful when it comes to knocking down 'brick walls', though close cousins can also play a part.


We can’t all be DNA experts – and the good news is that provided you follow the advice in this Masterclass, you'll be able to get amazing results even if you don’t understand the first thing about the science behind DNA. Indeed there are plenty of people who do know quite a lot about DNA who would probably achieve more if only they stuck to the simple strategies in this Masterclass!


Here's all you really need to know:


·       Most of the DNA tests on offer to family historians, and the only ones you should be seriously considering, are autosomal DNA tests; they can taken by both males and females, and they have the potential to solve puzzles anywhere in your family tree within the last 6 or 7 generations (around 250 years), but can sometimes reach back even further.

·       All of your DNA comes from your ancestors, but you inherit only half of your parents' autosomal DNA, they only inherited half of their parents' DNA, and so on. So always test the earliest generations.

·       Unlike personal traits and some hereditary diseases, DNA doesn’t skip a generation - you can't possibly inherit a segment of DNA from a grandparent unless your parent inherited it first

·       Just because you and your cousins share ancestors this doesn't necessarily mean that you'll share DNA - you could have inherited different bits of DNA from the ancestors you share; the closer the cousin, the more DNA you're likely to share, but despite this distant cousins are often more useful (partly because there are so many more of them!)


Which test should you choose?

Don’t make your decision based on price; although all of the main DNA tests on offer are technically similar, what you're looking for is to get as many matches with genetic cousins as possible. Ancestry have by far the biggest database, with around 20 million users, and the only way to get access to that database is to buy the Ancestry test.


Note: you might think that 20 million is a small number compared to the population of the world, and it is – but it's large number compared to the number of people in the world who subscribe to Ancestry, which is closer to 3 million.


Most other test providers allow transfers – but Ancestry don't, and that's why it’s crucial to test with them. You can always upload your data to other sites later, but you can't go the other way. Another reason to choose the Ancestry test is the way they integrate DNA with family trees – it works really, really well (as you would expect from a company that has been in the genealogy business far longer than any of their competitors).


The rewards of DNA

The reason I tested my DNA, and persuaded some of my cousins to join in, was to knock down 'brick walls' that conventional research couldn't breach. The sad reality is that if our 'brick walls' have resisted our efforts for years (or even decades), it’s unlikely that they're ever going to come crashing down if all we have to go on are the records that have survived down the centuries.


DNA can help by bridging gaps in the records and compensating for errors, but it means adopting new and unfamiliar strategies, and utilising somewhat different techniques to the ones that we're used to. But if you follow the steps in this Masterclass you won’t have to go through the steep learning curve that I did, nor will you make the mistakes that I did in the early days, before Ancestry started selling their test in the UK.


Before you even get your results.....

DNA isn't a substitute for researching the records – you need both. So make sure that you do all the conventional, records-based, research you reasonably can while you’re waiting for your DNA results, so that when they come through you're ready to go. Don’t leave it until the last moment, because in my experience the results invariably arrive well ahead of schedule, typically 4 weeks or less rather than the 6-8 weeks that Ancestry quote.


There are two types of cousins

Genetic cousins are the cousins you find by testing your DNA – but usually you won't know exactly how you're related to them, indeed you might not have a clue what the connection is! And that's where documented cousins come in – they're the cousins you can fit onto your family tree because you know precisely how they're related to you.


The most valuable cousins are both genetic and documented, and there are several ways to come up with them:


You can't do the first two until you get your DNA results through, and it might be hard to persuade your cousins to test if you're still waiting for your own results, even if you offer to pay. But the fourth option is open to you right now, because there is a great source of documented cousins who have already tested – amongst the LostCousins membership!


Connect with documented cousins

Complete your My Ancestors page at the LostCousins site, ensuring that you have entered ALL of the cousins that you can find on the 1881 Census. Because your living cousins are descended from the branches of your tree it's the relatives from the branches who are most likely to connect you to them. For example:



3rd, 4th, and 5th cousins are ideal when you’re working with DNA. If you’re younger than me and your grandparents weren't born until after 1881 you could look at it this way:



Completing your My Ancestors page might take you an hour or two, but it's easy to do and could save you money – if you don't find some 'lost cousins' who have already tested you're likely to end up paying for known cousins to test.


But it’s not just about money – connecting with documented cousins who have already tested could save you hundreds of hours you might otherwise spend fruitlessly analysing your DNA matches. DNA is like a jigsaw puzzle – the more pieces you can fit in place the easier it is to figure out how everything else fits in. DNA matches with documented cousins are the edge pieces of the jigsaw.


Tip: start with all the relatives you can identify in 1841, whether or not you can actually find them on that census, then trace each of your branches (sometimes referred to as collateral lines) through to 1881. Remember that ALL of your living cousins are descended from the branches of your tree, so every branch and every twig is a potential link to a 'lost cousin'.


On my own My Cousins page there are 17 cousins who have tested (indicated by 'Y' in the DNA column), and 2 who are considering it (shown by an 'M'). If there is no entry in the column it's worth checking with your cousin in case they forgot to update their My Details page when they tested.


Tip: DNA status is only shown for cousins who you have connected with – it isn't shown for New Contacts, or relatives who have not been identified as cousins (and may only be related by marriage).


How your cousins can best help

Shared matches are the key – if you and a documented cousin match the same genetic cousin then it’s overwhelmingly likely that the genetic cousin is descended from one of the ancestral lines that you and your documented cousin share. When you view a DNA match with any cousin at Ancestry you can click Shared Matches to find out which other cousins you both match.


Note: Ancestry only show shared matches where both matches exceed 20cM.


If your cousins also tested with Ancestry ask if they would be prepared to make you a Viewer of their DNA results – this enables you to see ALL of their matches, whether they share them with you or not, and allows you to check for shared matches where the 20cM threshold has not been reached.


Note: as a Viewer or Collaborator you can see another user's matches and their ethnicity results, but you don’t have access to their raw DNA results.


Being able to see ALL of a documented cousin's matches enables you to benefit from the matches they've made with genetic cousins who share your ancestors but who don’t appear in your own list. Remember what I said earlier: just because you and a cousin share ancestors doesn’t mean that you'll share DNA. For example, the chance of two 5th cousins sharing detectable DNA is about 1 in 3, so most of your 5th cousins who have tested won't appear in your list of matches – but they might appear in your cousins' lists, so the more documented cousins you collaborate with, the greater your chances of knocking down your 'brick walls'.


Everything I've written about so far can be done before you get your DNA results, so that you can be ready to "hit the ground running" when they arrive. But if you've already had your DNA results it's not too late to go back and fill in the gaps – indeed, it would be foolish not to.


How to process your DNA matches

I'm going to assume for the purpose of this article that you tested with Ancestry – but don't stop reading if you tested elsewhere because some of the strategies can be used at other sites.


At Ancestry you'll typically have over 10000 matches with genetic cousins, and of those about 97% will be with 'distant' cousins, ie where the estimated relationship is 5th cousin or more distant. So you might think that the best strategy might be to focus on the top 3%, on the basis that if you can't make head or tail of those matches, your chance of resolving the more distant matches is negligible.


But you couldn't be more wrong – your 'brick walls' are most likely to be solved by matches that Ancestry regards as distant matches, and this is partly because nobody, not even Ancestry, can accurately determine precisely how close a DNA match is once you get beyond 1st cousins. For example, one of my 3rd cousins and closest collaborators is shown by Ancestry as a 5th to 8th cousin because the amount of DNA we share is lower than average (but still within the normal range for 3rd cousins).


This means that simply working your way through the list from the top isn’t a great strategy. It inevitably will lead to wasted time and frustration, not least because many of your cousins won't have trees, and many of them won't reply to your messages.


Fortunately 5 years of using Ancestry DNA (and another 5 years before that trying to use DNA at other sites) have taught me a few things. Here's how to get the best results and avoid all the wasted time and frustration…..


Upload a tree and connect it to your DNA results (no subscription needed)

I have a public tree connected to my DNA results, but it only includes my direct ancestors – this makes it useful for my cousins, but of little interest to name collectors and the like. It also protects the privacy of my living cousins, since their branches aren't included. You don’t need to have a public tree, but you do need to have a tree connected to your DNA to make use of the advanced features which I'm going to tell you about next.


Common Ancestors (no subscription needed)

The Common Ancestors feature, which utilises online trees to figure out how you and some of your matches are connected. It's something you could do yourself if you had an Ancestry subscription, unlimited time, and a brain like a computer, but having Ancestry do it for you will provide a real boost.


About 1.4% of my DNA matches are flagged as having common ancestors: but what really stands out is that more than half of them are distant matches, and some of them have very small trees, some with under 10 relatives.


You might be wondering how Ancestry can identify one of my distant matches as having Common ancestors when she has only 4 people in her tree – it’s because they're looking at ALL the tens of millions of online trees in their database, not just the ones that belong to my DNA matches. That's why you'd need unlimited time and a brain the size of a planet to do it yourself!


In this case clicking reveals that the common ancestors are our great-great grandparents William Pepperell and Mary Ann Burns – making her my 3rd cousin, though once again the amount of shared DNA is below average for a 3rd cousin, which is why she's shown as 4th to 6th cousin.


When the common ancestor(s) are shown click the name of the ancestor to see how the two of you are descended from that person (the information in the first column will be based on the tree you've connected to your DNA results).


Always bear in mind that online trees often include errors – just because you have a DNA match with someone doesn't mean that their tree is correct, although it certainly improves the odds! However the information for each generation will usually be supported by multiple trees uploaded by different users, which is another encouraging factor.


When I've verified the connection I add a brief note against the DNA match at Ancestry, then add the cousin to the tree on my own computer, which often entails adding a new branch. At this point it may be apparent that there are relatives I can add to the My Ancestors page at the LostCousins site (to find further cousins), and doing it there and then makes it sure that it isn’t forgotten.


ThruLines™ (no subscription needed)

Ancestry's ThruLines feature uses Ancestry trees in an attempt to knock down 'brick walls'. It was introduced before Common Ancestors, which it overlaps to an extent, but it's still worth checking out.


When you access ThruLines it displays the direct ancestors on your tree, generation by generation, and as you move the mouse over each box it indicates matches with genetic cousins who share that ancestor. Even if you don’t have an Ancestry subscription you can see how you’re connected to those cousins, and as with Common Ancestors the algorithm utilises all Ancestry trees, public and private searchable, not just those that belong ot your DNA matches.


However, if you don’t have an Ancestry subscription you can't view the trees of people who aren't DNA matches, and even for those who are matches, you can only see 4 generations of their direct ancestors (ie back to their great-great grandparents). Nevertheless, ThruLines is a useful feature that will provide many clues.


Tip: you don’t need an Ancestry subscription to view a tree if you have been invited by the tree owner, but without a subscription you can only contact other members who are DNA matches of yours.


Where ThruLines really pays off is when it knocks down 'brick walls', by suggesting possible ancestors who don't appear on your tree. These are usually highlighted in green (rather than pink or blue) - the screenshot below shows an example:



Tip: any clues you get from ThruLines™ should be carefully checked, just as you would any other hints – don't assume that just because the other person is a DNA match their tree must be correct.


Even if ThruLines doesn't break down any of your 'brick walls' immediately, bear in mind that it will be updated as other users test, and as those who have already tested add to their trees.


As you've worked your way through your Common Ancestors matches, and your ThruLines you'll have been able to make notes against many of your matches to indicate how you're connected to them. But still the vast majority of your matches, even your close matches, will have nothing against them. The next step is to fill in some of the gaps by making use of Shared Matches.


Shared Matches (no subscription necessary)

There are two distinct ways to use Ancestry's Shared Matches feature, and they won't necessarily produce the same results – this is because Ancestry only shows shared matches of 20cM or more.


The first way is to work through your close matches (the ones who share 20cM or more with you); this will reveal which of your other close matches they also share, even if they don’t have trees of their own, or have minimal trees. Don’t jump to unjustified conclusions – for example, just because cousin A is a shared match with cousin B, who shares your Smith and Jones lines, doesn't mean that cousin A also shares those lines, because the connection could be further back.


The second way to make use of Shared Matches is to start with the cousins whose connection you already know, thanks to Common Ancestors and ThruLines. Many of them will be distant cousins of yours, ie they share less than 20cM with you, but that doesn’t stop them sharing more than 20cM with some of your close cousins. For example, I have 8 shared matches with the 3rd cousin I referred to previously, even though Ancestry tell me that we only share 10cM of DNA.


The latter approach has the potential to pick up more shared matches, so it’s well worth doing.


Groups (no subscription needed)

Ancestry allow you to allocate matches to one of 24 groups, each identified by a coloured circle of a different colour. Precisely how you use the groups is up to you, but note that you can display all the matches in a group and search within that group.


I use blues and greens for my father's side of the tree and reds and yellows for my mother's side, but how you make use of the groups is entirely up to you. A match can be in more than one group so if, for example, you allocated a colour to each of your 16 pairs of great-great-great grandparents there would be just one dot against your 4th cousins, two against each of your 3rd cousins, and so on.


Even if you don't know precisely how you are related to one of your matches you might be able to allocate them to a group based on shared matches. This is a very useful technique for adoptees or others who have an unknown parent – typically the matches to focus on will be the ones that aren't in any groups.


Note: you can also 'star' matches – it’s like an extra group. I use this feature to highlight matches which are worth taking another look at.  


What to do next…..

Making use of the simple tools that Ancestry provides is a great way to make some headway, but you're really only scratching the surface - it's likely that your connection to over 95% of your DNA matches is still a complete mystery.


What you need now are some simple, straightforward strategies that will lead you to the matches most likely to help you knock down your 'brick walls':


Strategy 1: search by surname (no subscription needed)

Ancestry allow you to search the trees of your matches by surname, so that you can identify cousins who have the same ancestral surname in their tree as one of your ancestors.


There are two factors that make this a particularly useful strategy: one is that the search only looks at ancestral surnames, so ignores names that only appear in branches of your match's tree; the other is that the search looks at private trees as well as public trees (provided those private trees are designated as searchable, which almost all are).


Here's how to go about it:




Strategy 2: search by birthplace (no subscription needed)


As you will have discovered when working through your list of surnames, most of the time the surname of the ancestors you share with a DNA cousin doesn't appear in both trees - indeed, it's quite possible that the surname of your common ancestor doesn't appear in either tree!


The problem is, when your female ancestors married they generally took their husband's surname. This makes it more difficult to research female ancestors whose children were born before the commencement of civil registration, since baptism registers don't usually give the mother's maiden surname - usually the only solution is to find the marriage. By contrast you can continue researching your male ancestors even if you can't find their marriage.


Of course, this problem doesn't simply affect you and your research - it affects your cousins too; most researchers' trees become increasingly sparse with each generation. If you've only identified 10% of your 256 6G grandparents and your cousins have only identified 10% of theirs, the odds of finding out how you're related to a 7th cousin simply by comparing the names in your trees are pretty remote (a little more than 1% in this example, not great odds).


Another way to figure out the connections to your DNA cousins is to look for geographical overlaps - and here's how to go about it:




Strategy 3: look for overlaps with the more unusual components of your ethnicity (no subscription needed)

Most readers of this newsletter have mostly British, Irish, or western European ancestry. But some of you will have Jewish ancestors, or ancestors from outside Europe, and whilst ethnicity estimates can be quite misleading, they do provide another way of analysing your matches.


Here's what Ancestry show for one of my DNA cousins:



If Ancestry had detected a Jewish component of my own ethnicity this would be one of the matches I'd be looking at very closely.



Strategy 4: look for the 'elephant in the room'


Because we all have 'brick walls' in our trees there are parts of our ancestry that are a closed book - yet there will inevitably be clues amongst our matches, if only we look for them. For example, if - like me - you don't know of any Irish ancestors, but have lots of matches with cousins who do, you might begin to wonder whether one of your 'brick walls' is concealing a connection to Ireland. I can't provide you with a step-by-step guide - it's all about awareness (Louis Pasteur said that "chance favours the prepared mind").


But beware of the common situation in which you share a single DNA segment with lots of people who all match each other. This suggests that the people you’re matched with come from an endogamous population, one in which people generally marry within the same community - in this case you would probably do well to ignore the matches altogether as any connection is likely to be a long way back.


More tips



Technical information

Most of the matches we make with DNA cousins will be many generations back, since we have many more distant cousins than we do close cousins. The final column of the table below indicates roughly how many cousins you might expect to find if you and they all took the Ancestry DNA test:




Based on Table 2 from: Henn BM, Hon L, Macpherson JM, Eriksson N, Saxonov S, Pe'er I, et al. (2012) Cryptic Distant Relatives Are Common in Both Isolated and Cosmopolitan Genetic Samples. PLoS ONE 7(4): e34267. doi:10.1371/journal.pone.0034267

Revised using Ancestry DNA estimates for the chances of detecting cousins and the expected number of 1st to 6th cousins for those of British ancestry; the numbers for 7th to 10th cousins are my own guesstimates


Of course, in practice only a small fraction of your cousins will have tested - even Ancestry, by far the biggest providers of autosomal tests, have sold fewer than 20 million tests - but you can nevertheless reckon that the cousins you're matched with will be distributed roughly in proportion to the figures shown above. In other words, over 98% of your matches will be with relatives who are at best 5th cousins, and could well be 8th cousins or even more distant. This won't necessarily be apparent when you look at your list of matches because there's a tendency for matches to appear closer or more distant than they really are.


Tip: Ancestry won't show any of your DNA matches as more distant than '5th to 8th cousin', but it's very likely that amongst them there are many who are more distant. Once you get beyond 3rd cousins the length of the shared segment(s) is only a very rough guide to how closely you are related - you could share a 20cM segment with a 10th cousin, but no detectable DNA with a 3rd cousin. The same limitations apply at other sites too, of course.


This amazing chart from Blaine Bettinger's blog shows how variable the amounts can be, and how this affects the amount of DNA shared by more distant relatives (there is a more recent version of the chart, but I find this one works better):



In each box there are three figures: the lowest and highest amounts shared between relatives of each order, together with the average. However the average only takes into account matches - if there was no detectable shared DNA it isn’t taken into account in the averages (but does show in the range).


What you will notice is that the average stabilises at around 12 or 13cM even for the most distant relationships in the chart. For example, you can see from the first table that the average DNA shared between 8th cousins is just 0.055cM, but the average in this chart is over 200 times greater. How can this happen? It's because unless there's a matching segment of at least 6 to 10cM most companies won't report a match at all - and because the chart only includes matches which were actually detected, it bumps up the average quite considerably.


Very interesting, you might think - but what does it actually mean in practice? What it tells us is that neither you, nor I, nor any of the DNA companies can reliably predict how closely we are related to our more distant cousins. So don’t rely on the testing company's estimate of how closely you’re related to a cousin, look at the chart and figure out what's possible, then consider what's likely (this means, for example, taking into account your age and that of your cousin).


Even if your DNA match is with a 5th cousin, someone who shares your great-great-great-great grandparents, it probably won’t be obvious how the two of you are related. I don't know about you, but I certainly can't say who all of my 4G grandparents were - indeed, I don't even know for sure who all my 3G grandparents were. I've got several 'brick walls' in the last 6 generations (though fewer than before I tested my DNA) - and most researchers, including my DNA cousins, are probably in the same situation. Go back another generation and there are even more gaps - and it just gets worse from then on.


In practice most of the ancestors that link us to our DNA cousins are on the other side of a 'brick wall' - and this could be a 'brick wall' in your own tree, in your cousin's tree, or both trees. What a fascinating challenge!



Peter's Tips

The exclusive offer I organised with The Genealogist (see last issue) expired on Saturday, but in response to requests from members I've arranged for it to be extended - just click this link. By the way, you can still watch Mark Bayley's excellent presentation here.


Talking of presentations, this year's competition was an experiment, but a very successful one judging from the feedback I've had from members who were lucky enough to attend some of the exclusive virtual events I organised for prize-winners. And for me it was a chance to put faces to the names of some of those I've been corresponding with for 10 years or more!



Stop Press

This is where any major updates and corrections will be highlighted - if you think you've spotted an error first reload the newsletter (press Ctrl-F5) then check again before writing to me, in case someone else has beaten you to it......



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Peter Calver

Founder, LostCousins


© Copyright 2022 Peter Calver


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