This post may contain affiliate links. Please read our disclaimer policy for more information.

So, what is Genetic Genealogy then?


I realised recently that I’d missed something quite crucial when I started this website up.  I’ve never explained what genetic genealogy actually is.  I realise lots of my readers are familiar with what genetic genealogy is already, but if you’re not?  Read on!


Genetic Genealogy as opposed to ‘Traditional’ Genealogy – what is traditional genealogy?

‘Traditional Genealogy’ is tracing your family history (or that of someone else), using documentary, source and other historical evidence to allow you to get as far back on a particular line or lines of your family tree as possible; in addition, you usually also use those same evidence sources to back up findings.


Ok, so genetic genealogy? 

Simply put, genetic genealogy is using DNA testing and analysis together with traditional genealogy – the DNA evidence becomes an extra piece of evidence or a clue as to where to look in historical and documentary sources.  By itself, at its best DNA testing allows you to work out the precise genetic relationship between two people, at worst it allows you to estimate that same genetic relationship.

DNA testing doesn’t replace ‘traditional’ genealogy, far from it.   It’s an extra tool in the arsenal of a genealogist but is best used in conjunction with traditional genealogical research sources such as vital, census and church records.

Three different kinds of DNA test

As I explained in an earlier article here, there are principally three different types of DNA test potentially of interest to the genealogist, autosomal DNA testing (which usually also gives an ‘X’ test analysis), Y-DNA (males only), and mtDNA (males and females), with most test companies now focusing on autosomal DNA because it is the most useful for recent genealogy.

Ok – so what can I ‘do’ with genetic genealogy?  And how do I do it?

As well as being a great way to find recent biological relatives, genetic genealogy has many other benefits.
If you have a brick wall in your tree or perhaps a commonly named ancestor and you can’t work out which one is your ancestor, DNA can potentially help you narrow down which is ‘your’ John Smith by finding John Smith in your DNA matches’ family trees, and prove or disprove your hypothesis as to who someone is.


Use case number 1 – NPEs / Adoptees/Foundlings / other unknown parentage cases.

If you have an ‘NPE’ event somewhere in your close tree, you can use your DNA results to try and identify who your direct relative is.  An NPE stands for ‘non-paternity event’, meaning misattributed paternity.  A clearer, more immediately understandable, plain English meaning is simply ‘not [the] parent expected’.  Yes, it’s usually the father who is not the parent expected.  As I wrote about, I used DNA to identify the unknown father of my grandfather, and am currently attempting to identify his maternal grandfather as well (what can I say, apparently there was not a lot to do in Ellesmere Port around those years!).


But how do you do this?

At a very, very high level, you look at your DNA matches, try to work out who potentially is on the ‘right’ side, try to identify that match, and build a tree for them (unless they have a verifiable tree on Ancestry or My Heritage etc. already).  You do that over and over again with your matches to try and find common ancestors between two or more of your matches.  Once you’ve found one, you work those trees forward to try and identify ‘suspects’ to be your unidentified person, looking for someone of about the right age who is in the right place at the right time.

Obviously the actual process you use to do the above work varies on a case-by-case basis but essentially involves what I like to think of as the magical four key ingredients – good old fashioned detective work (a.k.a. scary stalker skills), data analysis (a.k.a secret genius skills), research (a.k.a super librarian skills) and logical reasoning (a.k.a. channelling Sherlock).  There are also two other personality trait based ingredients which are my extra ‘umami’ for the best genetic genealogists; – extreme stubbornness and determination. The ability to be like a dog with a particularly good bone; once you’ve got your teeth around your problem you just won’t let go until you’ve found an answer.

The techniques I describe above are the same as used in forensic/investigative genetic genealogy to identify unidentified bodies and perpetrators of serious crime, it’s just a little more complicated.  The techniques are fundamentally the same though.

Use case number 2 – ‘proving’ your paper trail, and working out exactly which bits of your DNA came from who.

This is science super awesome, and my new favourite thing for my own tree!

Unfortunately, it’s currently difficult for those with primarily recent British ancestry purely because British DNA testing for genealogy purposes is still way behind the US, we haven’t yet reached ‘critical mass’ in Britain. So unless you can persuade known cousins and relatives to test, its a bit of a waiting game.

Essentially genetic genealogy of this type involves analysing your raw DNA against the raw DNA of your DNA matches, and working out which specific bits of your DNA you share, and therefore which of your common ancestors is responsible for that bit of DNA.  Super cool, eh?

But how?!

Until fairly recently, you’d do this by looking at your DNA matches in Gedmatch or at one of the sites that has a chromosome browser, with Excel or some other data analysis software.  However, there is now a fabulous online tool written by Jonny Perl, called DNA Painter, which allows you to create numerous profiles, and map your DNA results and matches across different platforms. This is called Chromosome Mapping. You can’t do it with Ancestry results (unless you can persuade your matches to upload their DNA to Gedmatch, FamilyTreeDNA or My Heritage) but it’s possible to do at the just mentioned sites and also 23 and Me, provided your match has agreed to share that data with you.

It’s a fairly complex area for newbies to DNA testing and genetic genealogy, but there are some tutorials and good information available, for example here:

Kitty Cooper – Using your DNA test results – the basics for genealogists

DNA Painter – How do you use DNA Painter?

Jonny Perl – Painting your DNA with Inferred Matches

Blaine Bettinger – DNA Painter (Youtube)

I am looking forward to getting to do this more in 2019, so will share my experiences here on my blog!

Do I need to understand the science of DNA to do all of this?

My opinion differs with some other people on this point – my answer is ‘not necessarily’.

You need to understand the difference between the different types of DNA tests to understand which is the best for you to take, and you need to understand enough about how DNA works to understand how to analyse your matches and inheritance patterns.

Beyond that?  How much you should learn about the actual DNA is entirely dependent on your interest levels.   I think science is amazing, but I don’t have the best brain for science, so I struggle to understand and retain information about it, so I prefer to read up on specific things as and when I need to. You do you!  If you do want to learn more about the science of DNA however, these videos are pretty good:

Introductory videos from the Genetic Science Learning Center at the University of Utah

Free course – Biology – Genes and Gene Technology

Coursera – Duke University – Introduction to Genetics & Evolution

Youtube channel Useful Genetics

The excellent Khan Academy also has various Biology lessons you might want to check out here.

 If books are more your thing, you may want to check out these (note these are Amazon affiliate links):

A Brief History of Everyone Who Ever Lived – Adam Rutherford

The Gene – Siddhartha Mukherjee

DNA: The Story of the Genetic Revolution – James D Watson with Andrew Berry and Kevin Davies

Genetics for Dummies – Tara Rodden Robinson

Who we are and how we got here – David Reich 


An example from my own tree – finding my ‘Irish’ great-grandmother, Mary

It was a long-held family legend that Mary, one of my maternal great-grandmothers, was Irish and that her husband had stolen her away from Ireland when she was only 14 years old.  It was also thought that she had had two brothers, Edward and Tommy, who had come to live in England as well.


I was able to get the marriage certificate for this set of great-grandparents, and that gave me her father’s name (John) and occupation (cotton broker) as well, so I was hopeful that I would be able to find their family in Irish records, after all, I had a rough year of birth to work with.  But no – zero reference in any Irish records.  At the time I assumed this was because the records no longer existed – I was aware a lot of records were destroyed in a fire at the Irish Records Office during the Irish Civil War (for more details on that, see here).


As more Irish records came online I kept looking, but still no dice.  Then, when I checked Ancestry a few years later, I noticed that a public family tree had this line fleshed out, and showed Mary as being born in the UKNot only that, it showed her parents as being born in the UK as well! I must admit, my initial suspicion was that the person had found a census record that might fit, and hadn’t looked into it properly.  After all, I ‘knew’ my great-grandmother was Irish, that was what all my relatives said, so it must be true!


I decided to look into it myself, and lo and behold, everything seemed to fit.  There were brothers documented, there was a father John, a cotton broker, and they were easily findable on census records.  The 1901 and earlier censuses also clearly showed that their father’s name was John, and he was a cotton broker. I felt a bit dumb, it had literally never occurred to me to look in England for her because as far as I was concerned, she was Irish.

I made an ‘executive decision’ and decided to follow the line back.  It was clear the family was of Irish stock from their surnames alone.  They were also Catholic and appeared to have been in Liverpool for at least a couple of generations.  I eventually found that this family had migrated to Liverpool in the late 1840s, presumably to escape the potato famine.  I linked them to my tree but put a comment on that it didn’t fit the story we had believed, so there was a chance that this Mary was not my Mary. I hoped that one day I’d be able to prove this was indeed my family.

After I DNA tested, I instantly had matches to this side of the family, proving that the paper trail was actually correct and that the family legend was way off.  Mary was born in 1894, in Liverpool, and married in 1913, so was actually 19 at the time of her marriage; perfectly respectable!


Her story is rather sad though.  Mary lost her mother when she was 12, and her father at 14. There were no relatives to take her in, and so Mary ended up in what was termed a ‘bad girls’ home. Unfortunately the records don’t survive, and so I have been unable to ascertain why she was there, however, there are no criminal records for her, and the home in question was known for also taking in girls at risk of falling into ‘immorality’, which I can only take to mean girls of an old enough living on the streets at risk of being drawn into prostitution.

She was still at the home at the time of the 1911 census, and according to the historical records I was able to find, conditions at the home in question were very poor.  Perhaps the truth is that my great-grandfather stole her away from the home, and she thought anything might be better. Unfortunately not. Said great-grandfather apparently ripped away the crucifix from around her neck following their wedding and told her she was no longer Catholic.  He appears to have been a violent and abusive individual, and Mary was like a little mouse who spoke incredibly quietly.

Even though Mary’s life was not a happy one, I am glad to know her story, and that would not have been possible without genetic genealogy.


Other benefits of DNA testing

Location, Location, Location (and surname, surname, surname)


DNA test results can also indicate locations as to where your family may have been from (it can also disprove locations where your family were from in some situations), which can help you give you a place to establish where you might want to focus your research.

As I discovered from my family’s DNA test results, it can also indicate surname variants and changes.

What’s in a surname?


Y-DNA and autosomal testing are being used in genealogy for surname studies.  Surname studies and ‘one name’ studies are often run through FamilyTreeDNA, and those with particular surnames in their history can submit their DNA results so that the project organisers can try and find specific shared DNA markers which stem from particular ancestors.  Y-DNA is great for this since it can trace further back in time than autosomal, but it can only trace the direct paternal line.  It’s always worth checking if there are any surname studies for your family surnames on FamilyTreeDNA, as often there are great discounts available for DNA tests contributing to a project’s surname research.

When I looked at my test results for the first time, I found the surname Ryall had become Royal, and Astles was Astle and appears to have originated as Hassall.  King was still too common in my results to find any sure relatives on that side, but I did find evidence that we are related to MacGregors – possibly confirming another family legend that our Kings were originally from Scotland and had changed their surname from MacGregor at the time of the proscription of the MacGregor name in 1603.

Currently, I’m investigating whether the Tolls in my family were actually Toole originally, or whether the
spelling changed in two different ways, or whether Toole married into the Tolls.  Some males can use Y-DNA to work this out.  My father currently has the ‘honour’ of being one of only two people in his particular haplogroup, neither of whom match each other in a useful genealogical time frame, and although that branch on FamilyTreeDNA’s public haplotree indicates probable Scottish / Irish origins, it could indicate German, and the earliest Toll I’ve been able to trace indicates on a census that his father was Dutch.  So in other words, who knows!

For more information about one name studies, check out the Guild of One-Name Studies.

Why Y?

Y-DNA testing is also very interesting for males to find the ancestry of their paternal lines; and potentially it can confirm that a male is related to someone through a common paternal ancestor many, many generations back (unlike autosomal DNA, which is currently only believed to be helpful up to six(ish) generations back).   It can also potentially be used as evidence to show the likely surname of an unknown father.  Unless you’re my dad, who only has matches at Y12, all of whom have different surnames which indicates they match with a common ancestor before surnames existed – not particularly helpful!

What about ‘deep’ ancestry?

DNA can also give you clues about your ethnic origins, and Y-DNA/mtDNA can uncover the deep ancestral routes of your direct paternal and maternal lines.  However, although fantastic tools, I personally don’t really consider these to be part of genetic genealogy since for me genetic genealogy is trying to answer specific questions or uncover specific ancestors via DNA analysis.

Are there ethical or other concerns with genetic genealogy?

Simply put, yes.

Tests are expensive, particularly when you are talking about extensive Y-DNA testing.  However, prices for autosomal testing have dropped in recent years, and this year Black Friday was at its lowest ever; generally around the $50-60 mark. I would not be surprised if prices continue to drop.

A lot of people test for ethnicity (because that’s what the advertisements seduce them into doingbut are surprised when it a) tells them what they already know, or b) does not tell them what they already ‘knew’.  The latter can be devastating when it turns out daddy is not daddy.

Because this is a relatively new and developing science, and each test company’s prediction is only as good as its reference samples, an individual’s ethnicity results are updated regularly, which can really confuse consumers and upset those who become attached to certain cultural identities which then disappear on the next update.

Privacy concerns.  To me, this is not that different from privacy concerns with genealogy as a whole, but that is not to suggest that privacy concerns are not there.  I wrote about this in detail in this post.  Make sure you understand the policy for the company you choose to test with but don’t get put off by scaremongering media articles that contain no real evidence to back up their headline.

Know that you can protect your privacy far more by ensuring you don’t have a wide social media and internet trail – just google your own name/email address right now to see what an investigative genealogist (or anyone, for that matter!) would be able to find about you in 30 minutes!

If you do want to be found by potential family, or be able to help out in a criminal/unidentified body case, you can use a non-identifiable-to-you email address, that way if someone needs, they have a way to contact you that is not impacting upon your privacy too much, and you can choose whether or not you wish to respond.

Want to know more about genetic genealogy?

I’ll be launching my introductory course in 2019, but in the meantime, I’d suggest checking out the following:

ISOGG’s Beginners’ Guides to Genetic Genealogy for links to a wealth of resources aimed at the beginner

An oldie but a goodie (where I started): Wheaton’s Beginners Guide to Genetic Genealogy.

If you’d like lesson-type materials and don’t mind paying, then check out Blaine Bettinger’s DNA Central, and Diahan Southard’s Your DNA Guide (note, I am a paying member to DNA Central but have not gone in depth with Blaine’s materials yet – but it’s Blaine, so it’s going to be good.  I haven’t yet subscribed to Diahan’s video lessons but had the pleasure of sitting in two seminars of Diahan’s at I4GG earlier this month and she’s awesome, so again, her videos are going to be good).

If books are more your thing, I’d recommend these (note these are affiliate links to Amazon):

The Family Tree Guide to DNA Testing and Genetic Genealogy by Blaine Bettinger

Genetic Genealogy in Practice by Blaine Bettinger and Debbie Parker Wayne

The Adoptee’s Guide to DNA Testing by Tamar Weinberg (aimed at adoptees but useful info for all)

Genetic Genealogy: the Basics and Beyond by Emily D Aulicino (slightly older book but still useful information)

I’m also excited about this brand new book which has just arrived on my doorstep, which is a more general genealogy guide but also includes information about DNA: The Family Tree Toolkit by Kenyatta D. Berry.

I’m hard at work on a ‘Resources’ page which will feature a glossary of all the terms you might encounter and think ‘what on earth does that mean’?  Again, I hope to have that live during the early part of 2019!