‘ThruLines’ and ‘Theory of Family Relativity’

For DNA testers who have attached a decent sized family tree to their test results, Ancestry and MyHeritage have tools that trawl through your matches to find common ancestors.

On Ancestry this tool is called ThruLines and it’s one of the three options on the main page when you enter the DNA part of your Ancestry site.  Click the green ‘Explore ThruLines’ tab, and you’ll find all your known direct ancestors up to and including 5xG grandparent.  Hover your curser over the ancestor to see if there are any matches and click on the ancestor to review the matches and decide for yourself if they are valid.

On MyHeritage the equivalent tool is called Theory of Family Relativity.  You’ll find them as they occur on your DNA match list, alongside those matches for whom ‘theories’ have been generated.  Just click the ‘Theory’ alert and review what’s being suggested.  Alternatively, you can use the filter bar at the top of your match list to see only matches for whom there is a ‘Theory’.  You’ll find it in the menu if you click on ‘All tree details’.

My Heritage filter bar for DNA matches

All you need to make use of these two tools is a well padded-out tree, and to have that tree linked to your DNA results.  You can have several sets of DNA results linked to the one tree and they will all work with ThruLines and Theories of Family Relativity.

In both cases – Ancestry and MyHeritage – the suggestions are based on your tree and your match’s tree.  They draw upon these and on other trees and records in their database to suggest how you may be related to your DNA matches through common ancestors. Hence although they will only show up if you and the other person are a DNA match, they are based on the genealogy, not the genetics.

These suggestions can be really helpful.  They are, however, ‘theories’, ‘suggestions’, ‘hints’.  We must review them and confirm (or otherwise) for ourselves. In this sense they are not dissimilar to the hints that pop up on our trees.

A ThruLines success!
Here’s a very recent (yesterday!) example from ThruLines that enabled me to break down a long-standing brick wall.  George Gamble is my 4xG grandfather.  He married my 4xG grandmother (Hannah) in 1790, when she was 20 years old.  I assumed he would be about the same age and was looking for a baptism between around 1760 and 1770.  When this ThruLine suggestion first popped up on my screen each of the two columns was headed by a different George Gamble – mine with an estimated birth year of 1765 and the one on the left with a birth year of 1749.  It didn’t make any sense, but I thought maybe the two Georges might be cousins, and this might lead me to my George’s father, so I clicked on the ‘other’ George.

That George was married to Susanna, but I noticed that they stopped having children in 1789 – the year before my George married Hannah.  Might Susanna have died in that year, perhaps in childbirth?  I checked for a burial for a Susanna Gamble, and there it was – about 14 weeks after the last birth – possibly milk fever?  I then checked all the occupation references for this other George.  He was a clothier – the same as my George.  The 1790 marriage entry for my 4xG grandparents refers to ‘George Gamble of this parish, clothier, and Hannah Brook of this parish, spinster’, but makes no reference to George’s own widowed marital status.  This was, however, undoubtedly the same person.  My 3xG grandmother Betty was from George’s second family, with Hannah; Phebe was from his first marriage to Susanna.  I amended George’s birth year to 1749, added in his first wife and children, and was able to take his line back another two generations.  Thrulines updates every 24 hours, and so today this new version of the chart has appeared: one George at the top of both lines, with a birth year of 1749.

Chart showing an example from Ancestry's ThruLines

The green entries on this ThruLines chart are significant.  My DNA match here has only fifteen people in her tree, and Ancestry’s system drew upon other trees to insert the connecting generations.

In the example above you’ll note that I didn’t just accept the suggestion.  I dug around, clarified, verified and decided for myself that this was a genuine connection.  In fact, being a ‘half 4th cousin 2x removed’, this match and I share very little DNA – only 8 centiMorgans.  With such a low match I would never have explored our connection without this nudge from Thrulines, and yet this chart enabled me to break down a decade-long brick wall.

Having said all that, in the interests of balance I will also say that the suggestions offered up by Thrulines and the Theory of Family Relativity are not always correct.

There are several reasons why this might be so.

‘Potential ancestors’ based on others’ trees may be wrong
As we have seen in the above example, if you or your match have a gap in your tree – for example if your line ends at a brick wall, or if your line goes back several generations further than your match’s, ThruLines actually fills in gaps. If these suggested ancestors are correct this can be a huge help, but they are not always correct.

One of my early posts on this blog was about the advantages and pitfalls of using public online trees.  A key point in that post was that just because it’s on someone else’s tree doesn’t make it right.  However, the way the algorithms work is that they go with the majority.  Your tree may be beautifully researched and documented and may be absolutely correct, but if six people have copied the wrong research it is that which will show up as the way to go.

Here’s an example.
In every census, my 3xG grandfather Joseph Groves gives an age consistent with a birth year of 1816 together with a birthplace of ‘London, Middlesex’. On his marriage certificate he gives his father’s name and occupation as ‘William Groves, gunsmith’.  However, there are no local ties to help me to navigate back to William, because as a young man Joseph leaves London, spends twenty years in the West Midlands and then relocates to Yorkshire.

An 1817 baptism record in Lambeth looked promising, and although the father’s name is Joseph rather than William it was worth following through.  However, this Joseph (the son) is still in London in 1841, by which time my Joseph has moved on to Staffordshire.  In any case, this part of London, south of the river, was referred to as ‘London, Surrey’, rather than Middlesex.  This is not my ancestor.

Despite this, and even though I have named my Joseph’s father as William, ThruLines persists in offering up Lambeth Joseph’s mother (Susannah) as my 4xG grandmother.  Note again, that because it’s a suggestion, Susannah’s thumbnail is green.  Clicking through and looking at the trees on which this suggestion is based I see a completely different family for Susannah and her son, Lambeth Joseph.  There is no doubt that this is not my Joseph and Susanna is not my 4xG grandmother.

Ancestry's ThruLines thumbnail example

You and your match may be distant cousins on more than one line
One of my DNA matches and I have two fairly close ancestral connections.  We are 4th cousins along my paternal grandmother’s line and 3rd cousins once removed along my paternal grandfather’s line.  I found the second link by accident when I was working on a third person we both link to.  There is no way ThruLines could have worked this out.  Its job is to trawl until it finds a match – one match.

This matters because we might look at other fairly close shared matches and assume that our match is along the same line.  It’s also particularly important if you start to use a chromosome browser – which I will cover in a future post.  Chromosome browsers enable you to use known segments as a basis for placing other unknown segments, so it really matters that you have attributed a segment to the right ancestors.  In this case, working with the chromosome browser, I have since been able to work out which segments shared with my double cousin belong to which line.

In case you think this is a rare scenario – it isn’t.  I have at least three more examples just like this in my tree.

You or your match may have made a mistake in your research We all make mistakes, and it’s important to be open to that possibility and to review if things aren’t looking right.

There may be an unknown misattributed parentage in one of your lines
Since the hints are based on trees rather than on analysis of segments the fact that two testers share DNA does nevertheless mean they are related elsewhere.

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I hope this little run through ThruLines and Theory of Family Relativity has demonstrated to you their obvious benefits.  All we have to remember is to use them as suggestions and to work through it and decide for ourselves if it’s real.

This video from Devon Noel Lee at Family History Fanatics might help to consolidate some of the above information for you.

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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

So your DNA results are in! What now?

I first took a DNA test to help with my family research about eight years ago.  Although I’d done a little reading and understood the basics, I had no idea how to make practical use of the DNA.  In the absence of knowledge, tools and even significant tester databases my modus operandi was to contact my matches and ask if they would be prepared to work with me at trying to locate where, on our trees, we matched.  Some never replied but even with the ones who did it wasn’t a success, resulting in zero confirmed matches.  None of us really had any idea how to actually use the new information the DNA itself provided.  Now, when I look back at the people I contacted I can ‘read’ the DNA info regarding our match better and I can see why we never found / in some cases never will find our common ancestors.

Since then, there have been lots of developments:

  • Many more people have tested
  • People have emerged as ‘authorities’, writing books, blogs, and producing helpful videos
  • Facebook groups have formed where people help each other and again, some have emerged as leaders and experts
  • Ancestry and MyHeritage have developed their own tests aimed specifically at genealogists, and working increasingly seamlessly with the tree-building functions of their websites
  • Other people and companies have created tools for us to use alongside our DNA results to help us get the most from them

Eventually I decided to get on top of this DNA thing, challenging myself to see how far I could progress within one year.  I tested again, this time with Ancestry (so I could access their large database), I read books, watched videos, learned how to use some of the new tools, and I joined Facebook groups, asking questions when stuck.  More than two years have passed and I’m still learning, but these days I can usually work on a match without ever needing to contact the other person, just using information on the database.  Of course there remains much to learn.  I still read, seek out videos on specific learning points, and if I’m stuck on something specific there is always someone on the Facebook groups with apparently encyclopaedic knowledge on matters DNA.

Earlier this year I published five blogposts (starting here) about how we can use DNA to develop our trees.  They were aimed at the complete beginner with no knowledge, and in particular at readers who hadn’t tested and didn’t trust or understand that DNA can provide a very useful additional string to your bow.  I tried to cover a number of common objections and misunderstandings I see regularly in online discussions

I’ve now put together another little series of posts.  This time the focus is more practical: how can we put the theory covered in those earlier posts into practice?  These posts have grown out of many email exchanges with some of my own DNA matches in which I’ve tried to answer their questions or explain to them how we might be able to progress together.  Again, this series focuses on known sticking points – often discovered in working with my own DNA matches.  So if you’re reading this because we’re DNA cousins (Hello!) then this post, the next two, and others that will follow in spring 2021 are dedicated to you.  My hope is that by writing it here instead of (repeatedly!) in emails, it will help other new – or even not-so-new – testers, who are still finding out how to make the DNA work.

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Getting started: Looking at your results
I’m going to concentrate here on the two DNA testing providers mostly used by amateur genealogists: Ancestry and MyHeritage.  These companies are increasingly integrating their DNA service with their online tree function.  However, other testing companies will present the essential information in a similar way.

When you open up the DNA page on Ancestry or MyHeritage the options you’re presented with are pretty similar.

On Ancestry you’ll see:

  • Your DNA Story, including ethnicities, and breaking these down further into regions, counties and smaller areas.
  • DNA Matches
  • Thrulines

On MyHeritage you’ll see:

  • An Overview, where you can scroll down to access all the other options but where you can also see your ethnicities at a glance
  • Ethnicity estimate – the areas are broader (less focused) than Ancestry’s
  • DNA Matches
  • Tools

EVERYONE looks at the ethnicities first!
Many people take a DNA test purely out of curiosity for the ethnicities.  They have no knowledge of and no interest in their family tree.  Often, the people listed as your DNA matches who have no tree attached will fall into this category.  (The other possibility is that they have no tree because they don’t know who their parents are and have taken the test to try to find out.)  Whatever your reason for taking the test, this is almost sure to be the place you look first, and on the surface it’s the easiest part to understand.

Ethnicities are, however, the least ‘accurate’ part of the whole DNA testing journey.  They are based on a comparison of your DNA to that of selected people with deep regional roots and well-documented family trees from around the world.  These people are referred to as the ‘reference panel’.  Different testing companies arrange their panels in different geographical groupings.  They also use different algorithms.  What this means is that your ethnicities are only an estimate; and although of course your DNA doesn’t change, from time to time, based on all of the above, the testing companies will update their estimate of your ethnicities.  It also means that the estimate of your ethnicity will differ according to which company provides it.  Hence at the time of writing this my own ethnicity is estimated as follows (the largest area is first in each case):

Ancestry: England & NW Europe, Scotland, Ireland, Sweden, Germanic Europe, Wales
FTDNA: Scandinavia, West and Central Europe, British Isles and a dash of Siberia
MyHeritage: (The DNA data I put on here was uploaded from my original FTDNA test): Mostly North and West Europe with some East Europe and a little South Europe

That’s quite a range, although taken as a whole they are all European and all centre on the north and north-west of Europe if not actually the British Isles.  (And of course like many people I cling to the hope of deep down, being a Viking. 🙂 )  It’s advised that tiny percentages (like my Siberia) be taken with a pinch of salt, but certainly as more people test, ethnicities are becoming more accurate.  If something unexpected shows up at a high percentage it’s likely to be a reasonable guide.

Ancestry have taken ethnicities a step further with the integration of ‘Genetic Communities’ into their ‘DNA Story’.  The smaller (regional, county, locality) groupings referred to above are in fact a combination of genetics and genealogy: they draw upon the family trees of your DNA matches.  These are generally found to be very accurate and in my case have homed in on two very important areas of my ancestry.

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The important bit: DNA matches
For genealogy and family history enthusiasts, this is the most important information.  Whichever company you tested with, your DNA matches will be listed in descending order starting with those with whom you share the highest amount of DNA at the top, right down to the tiniest matches.  You will have a LOT of matches but you should start at the top.

Your matches will be placed into categories.  At MyHeritage matches are placed into ‘Close Family’, ‘Extended Family’ and ‘Distant Relatives’ with an ‘estimated relationship’ for each person.  At Ancestry the divide is at ‘4th cousins or Closer’ and ‘All Matches’, with matches arranged as e.g. ‘Full Siblings’, ‘3rd cousins’, ‘4th cousins’, and a more specific estimate for each person.

For each individual match you’re given additional information.

Ancestry provide:

  • the person’s name (or pseudonym) and maybe a photo
  • the amount of shared DNA, expressed as centiMorgans (cM)
  • the number of individual segments these cM are arranged in, and the largest segment
  • whether they have a tree, and whether it’s public or private
  • whether you have already added any notes

Click on the person’s name for more information:

  • links to your match’s tree(s) – there may be more than one tree, but only one can be linked to their DNA
  • whether Ancestry’s algorithms have identified any common ancestors in your trees
  • a link where you can compare your own ethnicity with your match’s
  • a link to a list of shared matches – people who match both of you
  • You will also see where you can add the notes mentioned above and where you can add the person to a group, using a coloured dot of your choice

MyHeritage provide:

  • the person’s name (or pseudonym) and maybe a photo
  • the amount of shared DNA, expressed as cM and also as a percentage of your total DNA
  • the number of individual segments and the largest segment
  • whether they have a tree and how many people are on it
  • A ‘notepad’ icon where you can make notes (icon is red if you have already made notes for this match)

Click on ‘Review DNA Match’ for more information:

  • lists of ancestral surnames in your trees, with any shared surnames highlighted
  • lists of people who match both of you (shared matches)
  • a comparison of your ethnicities
  • and right at the bottom something called a chromosome browser, in which you can see exactly where, on your 22 chromosomes, you and this person match.  (I’ll be looking at this in detail in a mini-series of posts about chromosome mapping early in 2021.)

For an explanation of centiMorgans see my earlier post on Using DNA to develop your family research.  See also the Shared centiMorgan Project chart that sets out the possible relationships for any specific cM range.  As a general rule, don’t spend too much time working on matches below 30 centiMorgans.

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This is what you can do straight away
My advice is to take a while getting to know how the information is laid out, and to take note of anything that leaps out at you. I say this for two reasons.  Firstly, there’s a huge amount of information there and it’s easy to become overwhelmed.  But secondly, it takes a while for the powerful computers to find all your matches and include them on your match list, along with their trees and lists of shared matches.  The following action plan focuses on what you can do straight away while you find your way around the system.

  • Look at your list of matches.
  • For the closer matches (at the top of your list) do you already recognise them? Are they known cousins, second cousins, etc?
  • For any closer matches (such as 2nd or 3rd cousin) that you don’t recognise but who have trees, can you compare your trees and find a common ancestor?  Bear in mind that second cousins are descended from the same great grandparents; third cousins from the same great great grandparents.  But be prepared to look a generation or so either side.
  • When you can confirm your first match and have worked out your Most Recent Common Ancestors (MRCA) you can assign this match to a specific part of your tree.  You now know your documentary research to this point is correct and there were no adoptions or unexpected paternity events along the way.  Making immediate use of the notes box means you won’t waste time looking again for your match.
  • If you’re using Ancestry you can assign this reasonably close match a coloured dot.  How you organise your coloured dots is up to you.  I have eight colours – one for each great grandparent.  Whenever I can confirm a new match I give them the appropriate colour dot for the part of my tree they slot into.
  • You now have the beginning of a guide for other matches for this part of your tree.  For example, a first cousin match may help you to place any shared matches to your maternal or your paternal side; a second cousin may help you to home in on a specific grandparent.  See my previous post on Asking other family members to test for more guidance on this.
  • With this in mind, look now at the shared matches for you and your confirmed cousin match.  Again, perhaps you already know some of these people.  Perhaps you recognise their surname from your tree.  If not, perhaps their own tree will guide you to the place where your trees merge: your MRCA.
  • Join an online group.  There are several groups on Facebook, but DNA Help for Genealogy run by Donna Rutherford is a good place to start. Gradually you’ll understand more and be able to make better use of more of this information.

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My next DNA post, on 15th November, will look at Ancestry’s Thrulines and MyHeritage’s Theory of Family Relativity.

I’m deliberately releasing this information in manageable, bite-size chunks.  However, if I’m going too slow for you, have a look at Donna Rutherford’s blogpost on Frequently Asked Questions about DNA.

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Note
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.