To think these DNA ancestry tests make no sense

What a rude reply to the poster - it doesn't matter what you believe about heritage, if an adoptee wants to take a DNA test to learn more about their biological heritage then that should be respected, not invalidated.

Of course their physical heritage would be important to them, not just their lived experience.

For someone claiming to be an expert you're coming across as badly informed as well as naive.

There have only been approximately 117 billion people who have ever lived (including people alive now) so it is impossible to have had as many ancestors as you state.

A friend of mine found out that he had a daughter, who he'd never known about. By luck, his wife had given him a DNA test as a gift, and his "long lost" daughter had also done a DNA test as a bit of fun. They were matched up , got in contact, and discovered that he'd fathered her just before going overseas in the Army. Her biological mother never told him she was pregnant , and never told her daughter who the father was. The father and daughter were both so happy to be reunited - it was like an episode of "Long Lost Family".

Mine shows my Finnish/Anglo heritage with a dash of Mongolian.

I'm trying to understand your original post, OP.
The 0.1% that you refer to: do you mean the sample that you give to Ancestry for testing is 0.1% of the total DNA in your body?
But surely as a genetics expert you know that your whole genome is contained in every cell of your body, so your results are 100% of your genome, not 0.1%.
If that isn't what you were referring to, please explain further.

There's a podcast called The Gift (I think, a people often gibe them as gifts) which looks at the 'secrets' that DNA tests have brought up. Some pretty obvious, dad isn't dad but some other really strange/unusual links.

Mine was also accurate based on what I know about my family in the past 200 or so years.

This isn’t correct.

It was very accurate for my dh.

Yeah, there’s no way to even explain how wrong your math is. You do realize you’re saying, “But there [are] only 50 million people here. And a million of them are Vikings.” Yes, that’s true. There are 50 million people in the UK today. A million of them aren’t Vikings. There haven’t always been 50 million. This may be shocking but the amount of people in the world grows every generation. To do recursive math like that, you’d have to know how many there HAD been each year, and I’ve just told you that the science SHOWS you’re wrong and so very wrong. Vikings were invaders in a Celtic land. Ffs, Irish has been spoken in Ireland since long before the Vikings.

The estimate is that, in the history of the world, only 117 billion people have ever successfully lived on earth and a lot of them lived short, brutal lives and died childless. So, 22 million billion ancestors…?

So if I were you, I’d stop proclaiming the sky is purple. Unless this is just one of those goady ridiculous Saturday night threads; it probably is. Regardless, no point in answering you anymore. You won’t listen to reason or science.

It's not that your maths is "wrong", but your interpretation is poor. I too did not read your initial posts as those of someone with a high level of genetics understanding, sorry.

(I wouldn't call myself an expert, but have degree level maths and some postgrad genetics study, amongst other things).

From what I hear, the "ethnicity" interpretations from these DNA tests are improving but I agree there are substantial flaws (eg if the tests aren't allowed in France!). I have serious concerns about privacy and consent - see username, I was not in contact with a relative who had done a test but that was the link through which I was tracked down.

So we are all descended from Viking’s because 40 generations ago we have more ancestors than people alive at the time? So doesn’t the same logic mean that we are descended from everyone alive at that time?

Just to give some context to the opening post...

https://www.townandcountrymag.com/society/tradition/a60755278/meghan-markle-nigeria-honor-quotes/

DH's ancestry results followed closely his family records to 6 generations- his heritage is very mixed with unusual combinations from several continents. It was bizarre to see the percentages corroborating what he knew.

Just my two cents as someone who doesn't have a degree in genetics

DNA tests are pointless without drawing up your own family tree.

I am on ancestry and me and my mum did a DNA test because her dad was unknown, other than he was a GI.

the results we got meant i was able to identify who my grandfather was. It involved some of my mums first cousins doing DNA to eliminate them as siblings, so after three years of DNA and document searches we knew who he was.

This also explained my high Scottish/irish heritage.

And the area of my largest DNA linkage of three miles in ireland is totally correct.

It worked for me my ancestor's came from Scotland on one parents side Wales on the other and we settled in England it came back Scottish Welsh and mainly English very simple and straightforward

My background is complex and my test results were surprisingly accurate.

She's being polite. You are talking nonsense, and need to listen to her rather than double down.

I am a genetics expert.

It's really not. The Vikings didn't get everywhere, albeit they were comparatively better travelled than most.

@CarolineFields, my degree was in genetics, but I'm afraid I don't recognise the language that you're using to talk about this.

I did mine out of curiosity because I started looking into my family history when I retired and got a bit of a shock to discover that a lot of things I had been told about my origins were seemingly not true. All relations in my parents' generation and older are dead now so I will never know how the misinformation arose and whether it was deliberate or not, but I thought I'd get my DNA tested just to see whether it linked to the country I thought my ancestors came from, or the one that my research pointed to. It agreed with my research, linking me to a specific area that matched birth and marriage records I had unearthed so I am as sure as I can be that everything matches and is correct.