To think these DNA ancestry tests make no sense

[CarolineFields]

So you get back a score of 40% Nigerian. Meaning out of the tiny scrap of DNA tested - less than 0.1% -40% of that matches the average population in Nigeria. But if those Nigerians are tested, they won't come back as 100% Nigerian, so 40% of 0.1% matches people who are likely to be told they are 50% not Nigerian?

And if you are in Iceland when you have that test, you are told you are 40% Nigerian, but someone in Australia can be told they are 80% Icelandic due to being compared to you and you cohort?

The "ethnicity results" which you are referring to are just a bit of fun and will change over time. For some people they're very accurate, others not so much. It's all done by comparing your DNA to that of many other people who have tested and who have a proven genealogy going back several generations. Mine is actually fairly accurate.

Where Ancestry and similar tests are more useful is for matching you with other test takers, telling you how many centimorgans of DNA you share. This helps you grow your own tree and research your family history by connecting with mote distant family members.

The problem is that the tests are often marketed as "find out what percentage viking you are" and people are presented with this long list of names and numbers and don't have the know-how to understand it.

Mine is very accurate based on knowledge I have of my family.

But families can be complex. There can be many surprises!

My was very, very accurate.

how do you know?

Adam Rutherford has some criticism of these, and as a geneticist I think his take is worth listening to. Personally, I did a test and it returned very narrow results which didn’t match up to what I understood my family complexities to be, and maybe that’s because it’s all about who else has taken the tests and it doesn’t really prove anything much at all, not that there even is anything to prove. Like said above, it’s sold on some romantic notion of weird Viking longings. It seems like the only people who bother taking these tests are people of one particular demographic group, albeit spread throughout UK, USA and Australia. I guess that’s the group who can afford this.

well, everyone in Europe North America, North Africa or Asia has Viking ancestors. Dont need any sort of DNA test to know that.

If you’ve ever watched DNA family secrets on BBC, you will see that it can be very useful in identifying heritage and where patterns occur. There have been cases featured of unknown parentage where the experts doing the testing have been able to identify the heritage of people adopted at birth. One case showed a ‘brown’ guy adopted by white parents who told him that his father was from Egypt, the experts actually identified that his father was Punjabi. It’s definitely worthwhile.

My DP is Kazakh, not a country I would expect to come up randomly. I bought him a test and it did indeed come back with Kazakh as the highest proportion so I’m pretty sure it was accurate. He had a smattering of ethnicities from along the ‘silk road’ line which would also make sense.

How did you come to that (incorrect) conclusion?

My family came back mostly German and hardly any French (we have a lot of French in the family and some German but less so). My mum was really pissed off with ancestry.

I know someone who did one of these and it told her that her father was not her father. Except that when they visited a professional geneticist the DNA showed that he was.

Mine was too. It was absolutely no surprise that half my genes are from the area around Roscommon and the other half are East Anglian. The 4% Norwegian was a bit of a surprise!

My mums was very accurate, it named 2 areas of ireland, her mum was from one, her dad from the other. They can both trace there families back a long way in those areas. She has no Scandinavian blood at all.

Ooooof. What a shock that must have been to the family. I was reading a stat about these DNA testing kits and something like 4% throw up a 'shocking' result, like in your friend's case. I wonder how many people take the results as gospel? All kinds of chaos could ensue. And it might be a bullshit mistake.

My main issue is I'm a bit of a tinfoil hat wearer when it comes to giving up my DNA to some random private company.

I really wonder about this. I have a disease that is virtually unknown in the west but rates are very high in Turkey (where it is well-known and studied) and all along the old “Silk Road,” so much so that it’s colloquially known as “Silk Road disease.” I know my paternal grandmother was Welsh, but I don’t know that much about my paternal grandfather’s family, or either of my maternal grandparents. I’ve thought about taking one of these tests but I guess I worry it won’t change anything?

From what I understand that is because the other people who take these tests are German rather than French? People forget how much culture influences this.

The internet dna kits are banned in France, so there will be a much smaller pool of data available. Probably only people who have emigrated. France and Germany are next to each other, so probably have a lot of crossing over heritage.

It nearly ended her parents’ marriage. That was why they had professional tests done.

i too wouldn’t send my DNA off.

It is not incorrect, it is correct, so if the DNA ancestry tests don't say that, then they are incomplete, aren't they - but incomplete is the least of their issues - they make no sense at all.

40 generations ago you have 20 hundred billion ancestors out of a population of 50 million in Europe about a million of whom were Viking, so not only was every European descended from Vikings, but every European is related to every Viking. many times. Many many many many many times! ( and I have rounded those number down!)

Vikings were also in North America, North Africa and Asia

Well l did mine because l was adopted, and wanted to know my heritage.

Is this the demographic you’re referring to?

We used the My Heritage tests as I was advised it would be the better option, the results came in a really cool little video and had an explanation of each ethnicity. There are other tests that focus more on inherited conditions but we did it for fun as DP joked he’s 100% Kazakh.

Yeah you don't understand how autosomal DNA tests work.

Autosomal is not about deep ethnicity, it's about cousin matching over the last 4 or 5 generations, 6 at a push. Once you get that far back the amount of shared DNA is tiny, and because of the way DNA recombines, it's entirely possible that you are a 5th cousin of someone and have no shared DNA at all.

Y-DNA tests are a very different thing but these are not offered by Ancestry or 23andMe, or MyHeritage, and only for biological males. As the Y chromosome does not mutate quickly, you can link up with other people and find earliest common ancestors much further back.

Again - whatever the marketing says, the Ancestry and other DNA tests are to find genetic relatives, not deep ancestral roots.

It is not going to tell you your "heritage" though. It is going to tell you where some people who match some of the 0.1% of DNA looked at live. Whatever their heritage. They might have lived there 20 minutes. They might not even live there at all, and have lied on their form - they are not under any obligation to tell the truth

And I would argue that your "heritage" is what you experience in your life, not some biochemical in your cells.