Recently a reader, Ian, dropped me a note suggesting that perhaps not everyone understands the 2-fer value of close family members who DNA test.
That’s “two for the price of one.”
Even just one family member like an aunt or uncle, or a great-aunt or great-uncle is a goldmine.
In the chart above, you, in green, obtained 50% of your DNA from each parent. Each of your parents gave you have of thier autosomal DNA.
Your parent shares approximately 50% of their DNA with their full sibling who is your aunt (or uncle,) shown in yellow.
Full siblings each receive half of their parents’ DNA, just not the same exact half. That’s why you need to test your own siblings if your parents aren’t BOTH available for testing.
You share about 25% of your DNA with any aunt or uncle, shown in yellow. Your 25% shared DNA came from your grandparents.
The Important Part
But here’s the really important part:
- ALL of the DNA that your aunt or uncle carries is your ancestors’ DNA too – even though you only match your aunt/uncle on 25% of their DNA.
- ALL OF THEIR DNA IS AS RELEVANT TO YOU AS YOUR OWN!
- The other 75% of the DNA that they have, and you don’t, was inherited from your grandparents. There’s no place else for your full aunt or uncle to receive DNA.
You can utilize the DNA of a full aunt or uncle JUST LIKE YOU UTILIZE YOUR OWN MATCHES.
Here’s the 2-fer.
- Anyone you match in common with your aunt or uncle is identified to those grandparents or their ancestors. That’s about 25%.
- Anyone that your aunt or uncle matches in common with another family member that you don’t match but where you can identify the common ancestor provides you with information you can’t discover from your own DNA.
Their Matches are “Your Matches” Too – ALL OF THEM
Yes, all of them – even the people you don’t match yourself – because ALL of your aunts or uncles ancestors are your ancestors too.
Think about it this way, if you and your aunt both have 4000 matches (as an example) and you share 25% of those – you’ll be able to assign 1000 people to that parent’s side of your tree through common matches with your aunt.
However, your aunt will have another 3000 matches that you don’t share with her. All 3000 of those matches are equally as relevant to you as your own matches.
This is true even if your parent has tested, because your aunt or uncle inherited DNA from your grandparents that your parent didn’t inherit.
So instead of identifying just 1000 of your matches in common, you get the bonus of an additional 3000 of your aunt’s matches that you don’t have, so 4000 total matches of your own plus all 4000 of hers – 3000 of which are different from yours! That’s a total of 7000 unique matches for you to work with, not just your own 4000!
|Total Unique Matches||7000|
Moving Back Another Generation
If you’re lucky enough to have a great-aunt or great-uncle, shown in peach, the same situation applies.
You’ll share about 12.5% of your DNA with them, so you’ll only share about 500 of your 4000 matches, BUT, all 4000 of their matches are in essence your matches too because your great-aunt or great-uncle carries only the DNA of your great-grandparents, giving you 7500 unique matches to work with, using our example numbers.
Every aunt or uncle (or great-aunt or great-uncle) will provide you with some matches that other family members don’t have.
Whatever analysis techniques you use for your own DNA – do exactly the same for them – and test them at or transfer their DNA file to every vendor (with their permission of course) – while you can. Here’s an article about DNA testing and transfer strategies to help you understand available options.
Their DNA is every bit as valuable as your own – and probably more so because it represents part of your grandparents and/or great-grandparents DNA that your own parents and/or grandparents didn’t inherit. Without aunts and uncles, that DNA may be lost to you forever.
If your parents or grandparents have multiple living siblings – test all of them. If they have half-siblings, test them too, although only part of half siblings’ matches will be relevant to you, so you can’t treat them exactly the same as full sibling matches.
While you’re testing, be sure to test their Y and mitochondrial DNA lines at Family Tree DNA, the only company to offer this type of testing, if their Y and mitochondrial DNA is different than your own. If you don’t understand about the different kinds of DNA that can be tested, why you’d want to and inheritance paths, here’s a short article that explains.
You can always test yourself, but once other people have passed away, valuable, irreplaceable genetic information goes with them.
Any DNA information that you can recover from earlier generations is genetic gold.
Who do you have to test?
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Back in June you promised to do a YDNA series. I have been waiting on pins and needles for this! I hope you do it! YDNA is confusing!
You’re right, and I will. I’m sorry it has taken so long. This recent dashboard change has kind of thrown a wrench in thing too.
A question…..my husband and son have tested Y-DNA (they match)…..they have over 1400 matches but none higher that Y-12. I have tested my husband at the Big Y 700 level, hoping to find someone that might be a higher match…but so far no luck. Any thoughts as to why this could be? Is it possibly because there was only one surviving son in each generation for many generations back? Would it make sense to also test husband’s surviving brothers? Thanks for any help or suggestions.
Yes, that’s possible. It may also be that no one else has tested. If you test a surviving brother, be aware that it’s possible they might not match. Also, if you test a surviving brother,do so at the lowest level. No need to spend extra $. It’s also possible that your husband has some very unusual markers or an unusual mutation that is causing the mismatch.
Is it possible to determine if there are unusual markers or unusual mutation? His Y-Dna is all Denmark for generations back. It would just seem with 1400+ matches, there would be one of those that would match higher than Y-12. His grandfather was an only son, so no 3rd/4th male cousins – Rather than brother, would it make sense to test his father’s brother’s son/grandson? Thanks for your help!!
Yes, that puts it back at least one generation. I can take a look for you at the markres to see if there’s something unusual through a Quick Consult. https://dna-explained.com/store/
Thank you for this column . . . it’s something that is so obvious that it’s frequently overlooked, and it needed to be mentioned. For those of us who lost our parents before dna testing could be accomplished (in my case, even before direct to consumer testing was dreamed of), aunts and uncles may be the only way to further our analysis. I fortunately was able to test a 90 year old maternal aunt born 16 years after my mother – the only relative left in that generation.
One small point though: your numbers are (reasonably) based on the best case scenario. As you know, however, there are other possible situations. If you go back a couple generations in almost any community there likely was marriage among cousins at some level simply because rural communities had fewer marriageable choices and social groups tended to marry within their own even in urban areas. In the US that won’t matter much when Irish marries Italian (as an example) but it can matter when both parents descend from the same general region even if there wasn’t close contact back in the “home” country. My own parents were each from families in Canada’s Maritime Provinces and I have found many distant cousins who somehow are related to both of them even though the two families were separated by 100 miles and never had any contact.
This doesn’t, of course, put the lie to your primary point, only adds a note of caution depending on the circumstances. And the bigger point is simply that for anyone serious about using dna for genealogical purposes, every available person who might add something to the database should be tested, with particular emphasis on the older generations.
Yes, and the percentages by necessity are averages too. I hope people don’t swell on the actual numbers but on the concept and test those relatives!!!
Great tips as always! I think I’ve been very fortunate when it comes to who in my family tested. It certainly made life and genealogical research easier. I’ll run it down.
On my dad’s side, my great-aunt and two of his first cousins tested. One from his maternal side and one from his paternal side. The great-aunt is on the paternal side. That would be his paternal aunt.
She definitely has matches my father and I don’t have. It’s really cool. I just wish some of them had trees. Talk about a double edged sword, right?
On my mom’s side, one of her first cousins tested. I also have a great-aunt on her side as well. I’m not sure if she’ll be tested any time soon. I have a first cousin that side tested too.
I suppose all that’s left is to convince my brother to do this for science!! Here’s hoping…. Dunno how I could convince him.
My half brother on my Mom’s side wouldn’t test either.
That’s a bummer. =( It’s hard to convince people to do it. When I had my dad and I tested, it was because my great-aunt wanted us to. For my mom, I asked for curiosity’s sake. Ironically, I got the better deal for HER test than I did for mine and my father’s. She had a good laugh about it!!
Great article. Recently, I have discovered a few second cousins thanks to DNA testing. That was so exciting!
Unfortunately, my parents and two uncles passed away several years ago. I have a surviving great aunt and great uncle (brother and sister) who are my dad’s first cousins, but they aren’t interested in DNA testing. How much of their DNA am I likely to share with them?
Both of my sisters and one niece have tested. I share approximately 50% with my sisters and 23.5% with my niece.
You’re likely to share about 12.5% with each of them. It’s in the chart in the article. I hope they’ll change their mind. Sometimes if you ask as a personal favor.
I can try!
I don’t have any living siblings, parents, aunts or uncles…sad on more than the DNA front! However, I’m testing as many of my 1Cs and my parents 1Cs as agree…really valuable! I’ve also “target” tested a number of 2Cs. The other group that I “target” test are more distant cousins who are a generation closer to my GGPs and 2GGPs.
One that paid off for us was finding a descendant of the woman we thought was my 2GGM’s sister. A long way back here in NSW, Australia and the paper records were very sketchy when they were born. In their married life, they referred to each other as sisters. Maureen, my target, lives about a kilometre from me and agreed to test immediately! She’s 3C to my Mum’s 1Cs and 3C1R to other descendants of my 2GGM who have tested. We now have beautifully triangulated segments to support what we found in later paper records. A bit off topic but it’s led to other matches and filling in the family story further.
I ask for “collaborator” access to their DNA matches on AncestryDNA. They’re all sitting there beautifully colour coded into groups waiting for new matches to come along or more leads on our more distant ancestors! Many have also agreed to transfer their data to other sites. 4th cousin and closer matches here in Australia tend to range from 250 to 500…so you’ve got to search hard for some of that gold!
Thanks again for another great post Roberta.
A couple thoughts. Try to find those lost uncles and aunts. We didn’t find my dad’s brother soon enough. And try to get all your siblings to dna test as soon as possible even if you are just getting into dna genealogy. I was only 18 months into it when I lost my sister.
But I did get my 3C1R to dna test. He was from my dad’s generation and my dad’s 3C. One generation closer to the root generation. And it made difference. Big difference. He only has one set of 2G grandparents born in America. And only his direct paternal line was born in the US. Everyone on his mother’s side, his dad’s mother’s side and his grandfather’s mother’s side were from Europe. Instantly, probably the only people with which I con match my cousin my 3G(his 2G) grandparents. And that has answered questions and opened new ones. Now if he’ll ydna test…
My other thought about my my Ydna test. I got my father-in-law to test. He too was trying to pin down his paternal lineage. I thought it would be neat to compare his experience to mine.
I want to list my number of matches and then his by markers.
12 markers – 15500 matches
25 markers – 1950 matches
37 markers – 51 matches
67 markers – 30 matches
12 markers – 150 matches
25 markers – 31 matches
37 markers – 4 matches
67 markers – 0 matches
And the 4 at 37 markers were from Southern Europe not the British isles!!! And the British Isles was the modal for his results.
Results can vary considerably. I still haven’t found any Fortune ydna match. My brother is a full brother. So we’d match our dad. And we match all the Fortunes we should match going back to the 1850s, so I’m confident of the ydna lineage back to my 2G grandfather. And because I finally found a cousin that matched a big Fortune sticky block of dna who traces to a Fortune from the mid 1700s, now I can look for other males that I match ydna test and ask them to test. Oh yeah – the 51 men I match at 37 markers? Not a single atDNA match.
I need to do 111 markers or go big with the Big Y test. Then I can confirm how closely I’m related to the ydna subgroup I match at 67 markers. maybe Ftdna will have a big sale of the Big Y soon.
Test as as many people as you can. As soon as you can. Cast a big net and go wide and deep. I’m going to find what I’m looking for and then I’m going to share it!!!
This article prompted me to ask you something. Quite a while back, you had an article about how to buy a DNA kit from Family Tree DNA, without it being for any particular person, so when you found a chance for testing you would have it available. Could you please provide a link to that article?
The reason is related: My grandfather on my mother’s side was born to Cortis Joe Watson, married to Mattie Ann Martin. They had 4 boys in a row. An then a few years later their only girl was born. She had 2 boys and 1 girl, Sharon. Sharon only had boys. As I was interested in the Mitochondrial from Mattie Ann Martin, Sharon had agreed to be tested. But before we had the chance she unexpectedly go sick and passed. So now the only ones I know who have that MT DNA are her two brothers, and her 2 boys. Thus I’d like to order a kit without knowing which one it would be for.
Same thing for some Y DNA. I don’t share the Watson surname, but my GG had so many boys there’s plenty around to test. My mother only had an identical twin sister so no new DNA to test there.
Thanks for your great column and all your help!
You can order any kit and put it under your name. When you know who it’s for, just call support and tell them the kit number, information and gender.
How about a question that is sort of related to testing aunts and uncles? I have no parents or their siblings to test but I do have results of several 2d,cousins 1 to 3 times removed.
My wild idea would be to try to get them all to move to GEDmatch and then find some way to combine the results (Lazerus?) in hopes of getting the DNA for the common great grandfather. The theory would be that doing that would cut out the DNA results of the wives other than the common great grandmother. Then, in theory, any matches might result in a better chance of finding the great great grandparents and the unknown daughter by great grandfather and his first wife.
Another theory would be to get them all to GEDmatch and then start running comparisons using the “who matches both results” and then doing it again and again until all the possible matches have been done….then looking for common matches to all the original samples.
No, not too wild. I’d do both. Be aware that Lazarus isn’t terrible dependable, but you can verify independently.
Thank you for this article. For my part, it is not easy to purchase the test kit because I am here in the Philippines. My maternal cousin in Canada agrees to help me. She will be the recipient and she will stay here for a few months before returning to Canada.
On my paternal side, my grandmother’s aunt is still alive. She is the only surviving among 10 siblings. She certainly has a lot of DNA that I don’t have anymore. Unluckily, due to this pandemic, travel restriction is not uncommon and she resides in a different province. I hope, it won’t be too late.
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