Just received my DNA results from ancestry

[Mart 'n' Al]

People should not take DNA tests if they just want their ethnicity results without watching this video.

https://m.youtube.com/watch?v=nlmK0X3I1Lo

It is such an excellent presentation, especially the data simulation. It should become required watching for anybody before they give their DNA, hoping to get extreme details of their ethnicity. It counters the YouTube videos of shocked people opening their DNA results on camera. It would also go a long way to explaining statistics to people who shouldn't be gambling. I will be citing this video frequently. One thing that tney don't mention is the absolute futility of researching your ancestry back more than a few generations because you are eventually going to encounter a non paternal event, i.e. somebody is descended from a secret relationship and this is not recorded anywhere except in your DNA.  You only have to go back 5 or 6 Generations, and you have looked at 100 relationships. You only need one man or woman in those 100 or so relationships to have had an illicit relationship producing a child and it makes a mockery of your further research.

Martin

[sugarfizzle]

Martin, There have been many posts/threads over the years in this forum about ethnicity, and there is plenty of advice given in return.

Your link doesn't appear to mention ethnicity, so I hope you are not 'going to cite this video frequently'   

And why should people not have an autosomal DNA test until they have seen any video?      Though lots are not interested in family history, and lots will ignore your emails, don't forget, the more people who test, the more matches we will all get, and someone will respond or have a small tree where you can work out the connection and perhaps break down a brick wall.

As for futility of researching one's tree back more than a few generations, I disagree.
There may be an unknown illegitimacy in my tree, there may well have been an illicit relationship.

But to say that research beyond 4G grandparent level, in my case to about mid 18C on most lines, is futile? ---

What about my granddaughter, should she only research as far as her 4G grandparents? That would be early to mid 19C. Why should she only go back 75 years later than me? And what about closer relationships, great grandparents or 2G grandparents? If one of those is incorrect it makes a whole mockery of your tree. As for your mother or grandparents having illicit relationships, half to a quarter of your tree could be based on fallacy.

To a certain extent you have to trust that your ancestors had good values, didn't commit adultery, or didn't take in children as their own if they were found in the street, or were their grandchildren.

First children, especially those conceived before marriage, are perhaps more likely to be NPEs, but impossible to prove/disprove. That's where hopefully autosomal DNA comes in - no matches at all on one line could indicate an NPE, but may just be dilution of the DNA (which your link actually talks about, not ethnicity).

The people who you will be sharing your link with will mostly already have taken DNA testing, so will not stop them from being disappointed or shocked.

Lots of smiley faces in this reply, as I don't want to offend you, or anybody else for that matter, merely expressing a different point of view.   

Regards Margaret 

[Mart 'n' Al]

I never profess to be able to please all the people all the time.  There is so much snake oil on the internet and it is very much a case of caveat emptor, but I thought the content and presentation of that video was second to none and everything that was said was relevant to people looking for their ethnicity estimates, and I will be continuing to recommend it to anybody who asks for help. I have no connection with the organisation who produced it.

I am a mathematician and statistician and I have rarely seen such a complex subject explained so succinctly. You only need one person in your relatively recent heritage to have been euphemistically playing away from home to totally scupper the relevance of your research. I am starting to repeat myself.

Finally I will add that my own research has proved without any doubt that the legal documents I have uncovered tell a very different version of my ancestry than I had been lead to believe for more than the last half century. 

I will leave it to Mark, who posted earlier today, the one to which I was replying, to take my advice or leave it.

Finally I very much recommend the recommended video which I recommended in my earlier recommending comments of recommendation.

Martin

[sugarfizzle]

But Martin, the link does not allude to ethnicity. I am tempted to say 'at all', but I only watched it once, so cannot say for sure.

It is talking about why we do not inherit much DNA from more distant generations, and how DNA recombines at some stage, and why we always inherit 50% from each of our parents, but not exactly 25% from each of our grandparents, thus not exactly 12.5% from great grandparents etc. etc.

It was an interesting video, nonetheless, but nowt to do with ethnicity.

Regards Margaret     

[Mart 'n' Al]

I'm sorry, you only paid for a 5 minute argument, and you've had five minutes. Everything in that video explains why people struggle to understand their ethnicity estimates.  (Except for me, and I'm still struggling with my supposed  8% Greek...)

Here's another of my recommended videos:

https://m.youtube.com/watch?v=Lvcnx6-0GhA

Martin

[sugarfizzle]

I am paying for one more minute, after which I will not comment on this thread again, unless directly invited by your good self. I am not trying to be difficult, I can assure you.

You have seen an excellent YouTube video, presumably which helps people understand why their ethnicity results are not as expected. I don't know, as I haven't seen it.
You link to a YouTube video which helps people understand why 'You might be related even less to your ancestors than you thought'. This is by Andrew Lee and is quite informative, but doesn't relate to ethnicity. It is about how we inherit less and less DNA from ancestors with successive generations.
Your really excellent video, which I would love to see, is not linked to at all, i.e. your link is incorrect.

Either that, or my tablet and phone don't work properly, I get the same video on both.

If you give the title and presenter, I might be able to find it myself.

Regards Margaret

[Gan Yam]

I have watched the video and it was quite interesting, but did contain some errors.  One of the tables showed a negative amount of DNA inherited.  You can only inherit some or none!

I haven't had my DNA tested, but am considering it, but it does confuse me and wonder whether its worth it.  I would like my brother to have a YDNA test as our g/father was the result of an "illicit liaison", but he wont and he's the last of the line, so that's that. I can see that although there was no mention of ethnicity in the video that conslusions can be drawn as to why you get some of the results that you do, as you lose DNA with each generation that you go back to.  I think ethnicity results can only be limited, because of the amount of people tested and probably should be taken with a pinch of salt.
After watching other of the guys video he does say that we share 95.5%-99.9% of our DNA with our ancestors, its only a small proportion thats randomly shared. He also says that you are only genetically related to about 120 ancestors but are genealogically related to them all.

If DNA is inherited as up to half (approx) of each person in each generation then surely DNA is unable to prove or disprove that someone 5 or 6 generations back is related or not, as you may not have inherited any of their DNA but they are still your ancestors. If you only research 4 generations back then presumably the current researchers will be the last generation to research, as future generation have all the info that they need.

Whether you share some or no DNA, (are genetically or genealogically related) to your 10x g/parents if they hadn't got together then you wouldn't be you, so every generation is worth investigation, DNA can only to a tool? It proves nothing/it proves everything?? 

[Old Bristolian]

Returning to the ethnicity question which kicked this thread off, my lineage as discovered by tradional paper trail research is virtually wholely southern English. I do however have an unknown grandfather whom I would obviously like to identify. My ethnicity results indicated 34% Scots and then mainly English. Although I agree that the ethnicity element is not to be trusted in general, my matches show a large number of people who are Scottish or have Scottish ancestry - very interestsing to me and a partial confirmation that I should be looking at a Caledonian grandpa!

Steve

[IJDisney]

People should not take DNA tests if they just want their ethnicity results without watching this video.

https://m.youtube.com/watch?v=nlmK0X3I1Lo

It is such an excellent presentation, especially the data simulation. It should become required watching for anybody before they give their DNA, hoping to get extreme details of their ethnicity.

Its an interesting presentation, but he contradicts himself. At 4.20 he says "about three quarters of our six great grandparents we don't share any DNA with". That suggests that we only share DNA with about 64 people at that generation. But later on, with his simulation from about 5 minutes in, the chart shows that we could actually share DNA with up 93 out of our 256 6 x great grandparents (which is over a third). A small point, but in mathematics a small variant can throw out a huge error in the long run. His maths also doesn't allow for any cousin marriages (a huge factor in my opinion) which will throw his conclusions way out too.

But I get the point. Basically, DNA can only prove part of our ancestry, since we don't inherit DNA from every one of our ancestors. Therefore ethnicity estimates are only based on the DNA markers we have inherited from a certain percentage of our ancestors (not all our ancestors). So even if the ethnicity estimates were accurate (I am aware that they are not!) it will ignore a huge percentage of our ancestors whose DNA we have not inherited.

Therefore if I get told I'm 79% Irish/Scots and 21% North European, yet I believe that one of my 3 x great grandparents was from Indian, and another was North African, then I should ignore the estimate and go with my family knowledge (if I have document proof, of course). Equally, if i didn't know about those ancestors, and believed the ethnicity estimates were accurate, I might ignore possible future leads that would lead to me finding them.