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Old 11-20-2017, 10:18 AM
 
6 posts, read 1,908 times
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I understand the concept of DNA databases. However, is every ethnicity conclusion drawn specifically from whichever database is being used?

If so, then doesn't the relative makeup of the database participants actually determine the ethnic group parameters to begin with?

I'll use an extreme example for what I'm trying to ask. Let's say there is a DNA database of one million people. Let's say that there are 200k people from Germany who have submitted DNA. Now let's assume all of those 200k are the pure descendants of Turkish immigrants. Would the DNA of those 200k shape the standard of what constitutes German ethnicity (or Northwest European, et al) for the entire study?

I guess another way to put it is "Are these DNA companies using any starting point pre-database?" If not, then all databases are skewed by any and all recent immigration to any region.

I would hope there are certain genetic markers that science has decided unequivocally belong to certain indigenous/historic ethnic groups. I would hope that every company would use some sort of stand-alone precedent before they look to their databases. If not, then I don't see much point in any of this.

I hope someone can explain, because I was very interested in ordering a kit until reading some things about the databases.
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Old 11-20-2017, 02:18 PM
 
Location: Colorado (PA at heart)
9,255 posts, read 14,298,122 times
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Quote:
Originally Posted by Sli624 View Post
I understand the concept of DNA databases. However, is every ethnicity conclusion drawn specifically from whichever database is being used?

If so, then doesn't the relative makeup of the database participants actually determine the ethnic group parameters to begin with?
Most companies determine ethnicity by having a reference panel of samples they compare each tester to. The commercial testers aren't a part of the reference panel - the samples for the reference panel are collected separately. So there's the sample database, and there's the testers database, and the latter gets compared with the former - testers don't get compared with each other, not for ethnicity.

AncestryDNA has 3,000 samples in their reference panel and 6 million testers, 23andMe has 10,000 in their reference panel and about 2 million testers, and FTDNA has 2,943 in their reference panel but haven't released their number of testers. MyHeritageDNA won't release either data.

Quote:
I'll use an extreme example for what I'm trying to ask. Let's say there is a DNA database of one million people. Let's say that there are 200k people from Germany who have submitted DNA. Now let's assume all of those 200k are the pure descendants of Turkish immigrants. Would the DNA of those 200k shape the standard of what constitutes German ethnicity (or Northwest European, et al) for the entire study?
No. The closest thing to that is AncestryDNA's "Genetic Communities" but these are different from the ethnicity percentages and aren't exactly what you're describing either.

Quote:
I guess another way to put it is "Are these DNA companies using any starting point pre-database?" If not, then all databases are skewed by any and all recent immigration to any region.
That's precisely why they don't do this. The samples in the reference panel need to be controlled as much as possible. They only accept people who can trace their entire ancestry within one general region as far back as possible. AncestryDNA actually started with over 4,000 samples but ruled out many of them as not being reliable enough and ended up with 3,000.

Quote:
I hope someone can explain, because I was very interested in ordering a kit until reading some things about the databases.
What are you reading about the databases?

You should be able to read AncestryDNA's White Paper on determining ethnicity here: https://www.ancestry.com/dna/resourc...hite-Paper.pdf - if that doesn't work, maybe I can add it as an attachment. I would stick to reading data from the companies, if that's not what you were reading.

Here's 23andMe's info: https://www.23andme.com/ancestry-composition-guide/

And from FTDNA: https://www.familytreedna.com/learn/...s-methodology/
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Old 11-20-2017, 02:46 PM
 
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@PA2UK That is great news. Thank you for answering every detail. It is a load off my mind, as I am very interested in doing this, entirely for ethnicity purposes.

What I had been reading over and over again was that a company's ability was limited by its database and that without the database there was no reference. I seemed to come across that every time I google searched, and I heard that on youtube again and again.

Thank you very much for spelling out the truth comprehensively!

If you don't mind another question - any idea why MyHeritage won't release the reference panel data? I was leaning towards them.
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Old 11-20-2017, 03:44 PM
 
Location: Colorado (PA at heart)
9,255 posts, read 14,298,122 times
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Quote:
Originally Posted by Sli624 View Post
@PA2UK That is great news. Thank you for answering every detail. It is a load off my mind, as I am very interested in doing this, entirely for ethnicity purposes.

What I had been reading over and over again was that a company's ability was limited by its database and that without the database there was no reference. I seemed to come across that every time I google searched, and I heard that on youtube again and again.
Well, yes, that is true, the reference panels are limited and different companies have different panels and without those panels, there's nothing to compare your DNA with. When you consider they only use about 3,000-10,000 samples when there are billions of people in the world, it is a very limited panel. The different companies also use different algorithms for the comparisons with your DNA and the reference panel, which means you'll get different results from different companies. If that's what you were reading then it's true, and it's important to understand that all ethnicity reports are merely an estimate.

Quote:
If you don't mind another question - any idea why MyHeritage won't release the reference panel data? I was leaning towards them.
Definitely don't buy MyHeritage's DNA test. For starters, they accept free uploads from other companies, so if you test with AncestryDNA, for example, you can get results from MyHeritage for free. But it doesn't work the other way around, AncestryDNA and 23andMe don't accept data from other companies. So it makes more sense to test with one of them and then upload MyHeritage. You can also upload to FTDNA, but it costs $19 to unlock your full results (still a good deal though). Secondly, MyHeritage are the worst of the bunch. Their ethnicity report is the least accurate in general, and their DNA relatives/matching with other testers is unreliable (lots of other false negatives or false positives - I wrote on my blog about it with details here: Genealogical Musings: MyHeritageDNA Matching Issues ). They are newcomers to the DNA field and I don't think they've gotten themselves sorted out yet.

AncestryDNA will undoubtedly be doing their Black Friday/Cyber Monday sale so if you're looking into MyHeritage because it's cheaper, I'd wait for AncestryDNA to go on sale.

I couldn't say why they won't release that info though - unless maybe the customer service rep I spoke to just didn't have that info and couldn't be bothered finding out, but I just checked the email and the official word was "I am not at liberty to disclose this."
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Old 11-20-2017, 05:02 PM
 
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Very good advice. Thank you. It definitely makes sense to use a service that won't read other service's data, and then upload it freely or cheaply to others. One thing I have just read though is that the new 23andMe kits are using a new chip - v5, and it is not readable by most other services...at least not yet.

I plan to read your blog now. Thanks again!
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Old 11-21-2017, 09:45 AM
 
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Keep in mind that this type of ethnic analysis from your DNA is a very new science and can be very inaccurate. Many people before they test assume that the companies can accurately divide your ancestry into neat categories with percentages. And that is what they try to do, and advertise people smiling over their pie charts, but for several reasons it is often impossible to do that. Populations have been mixing and migrating for millennia, so the DNA from one population can be similar or identical to other populations.

Especially if you are interested in finding "German DNA", there is really no such thing. People with German ancestry share their deep ancestry with British, Scandinavian, French, Spanish, and other European ethnicities. None of the companies are particularly good at telling you if you have specifically German ancestry.

For example I have one grandparent who is fully German, going back as far as we can trace into the 1600s. The rest of my ancestors are primarily British in origin, So approximately 20-30% of my ancestry is German. Here are my results in the tests I have taken:

FamilyTreeDNA: 50% "West and Central Europe" (this covers Germany; there is no specific category for Germany)
23andMe: 7% "French and German" (they lump both together because they are so historically intertwined)
AncestryDNA: 15% "Europe West" (again, this is their region that includes Germany, there is no separate category limited to Germany alone)
MyHeritage: 0% of anything that would include Germany, instead they give me erroneous Italian ancestry at 22%.

As you can see, none came close to assessing my actual German ancestry through my DNA. And yes, I know from cousin matching that my German grandfather was my biological grandfather and his relatives share the same ancestors born in Germany.

So you might ask, why did I waste my money on these tests? Because I was not interested in ethnicity estimates, I am interested in cousin matching.
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Old 11-21-2017, 10:31 AM
 
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I know many of the services won't say "German". From what I've read, MyHeritage does...but from you've said, I'd have to take their results with a grain of salt.

Actually, I'm not concerned about "German". I'm interested in the overall ethnicity breakdown of my DNA. My father's heritage is German. My mother's is 1/2 German and 1/2 Polish. I assume those ancestors were the same as most of what are considered ethnic Germans and ethnic Poles.

So for the German 3/4ths, I am expecting mainly "Northwest European" with the possibility of some Slavic, Baltic, Scandinavian, Ashkenazic, etc. DNA. For the Polish 1/4th I am expecting mainly "Eastern European" results, with the possibility of Baltic and maybe others.

Yet I also know that I may have very little of my maternal grandmother's (the Polish grandparent) DNA, so maybe I will have very little Slavic DNA. And I know it won't breakdown what I got from which parent. That is unimportant to me.

When I get my results and see a percentage of Eastern European, I won't automatically conclude it's all from my Polish quarter. When I see a percentage of Northwestern European, I won't automatically assume it's all from my German 3-quarters.

What I'm interested in, at the end of the day, is my ethnic DNA breakdown plain and simple. I actually couldn't care less about "German" or "Polish" or what came from which ancestor. Northern Germans are more closely related to the Dutch than they are to southern Germans, and eastern Germans are no more closely related to western Germans than they are to Poles, etc., etc., etc. I know all about the research. I'm looking at my ethnicity from a genetic standpoint and do not have much interest in countries, language, culture, etc.
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Old 11-21-2017, 04:30 PM
 
Location: Colorado (PA at heart)
9,255 posts, read 14,298,122 times
Reputation: 12070
Quote:
Originally Posted by Sli624 View Post
One thing I have just read though is that the new 23andMe kits are using a new chip - v5, and it is not readable by most other services...at least not yet.
That's true, although I thought I heard there's a workaround for it. In any case, it's usually just a matter of time before the other companies "catch up" to a company's new chip.
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Old 11-21-2017, 04:34 PM
 
Location: Colorado (PA at heart)
9,255 posts, read 14,298,122 times
Reputation: 12070
Quote:
Originally Posted by Sli624 View Post
I know many of the services won't say "German". From what I've read, MyHeritage does...
No, they have "North & West European" which includes but is not limited to Germany. I am roughly 25% German and aries63, I am also missing any results in North & West European on MyHeritage. Part of the reason I say their reports are the least accurate.
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