View Full Version : Just How "accurate" is autosomal DNA ethnicity

11-02-2016, 06:05 PM
I am just curious.

I have mixed feelings on the accuracy with most of it been low. But then that might be cause I know the family lineage quite well and yeah when sites like gedmatch can't identify German is a quarter German person [instead saying rather English] it makes one chuckle.

So what would you say for accuracy? And if you don't mind sharing how far have you traced your lineage. How complete is your knowledge of your family history?

Oh and by accuracy I mean if your family is generally from X area and ethnicity is saying Y area. Yes there's waylay for overlap, etc., but if you belong to again X area and Y area is half way across the world you got to laugh.

11-02-2016, 06:39 PM
I couldn't honestly say . These calculators cover 500 years or more back and that's a lot of unknown ancestry for me.

11-02-2016, 07:18 PM
It's pretty good, although you have to remember to not take things absolutely literally, but rather look at your results in the context of surrounding populations - as most geographically close populations are quite similar in autosomal makeup. Also bear in mind the reference populations are generally averages, so it's perhaps more useful to try and look at a good number of results of other people with similar ancestry to see what is within the range of being typical. As for example you may get 2% more on one component and 2% less on another, which may make the oracles find the best fit for your ancestry as 90% x and 10% y, when in reality you are 'normal' for that population. Although it works the other way two, like if you are a mix of two closely related populations it may not even pick up on it, or not in the right proportions. That doesn't mean that you aren't what you think you are. In theory if you were a perfect fit for the reference population in all of your different ancestries it would probably get it correct, but no one is, pretty much.

11-04-2016, 10:20 PM

11-05-2016, 08:26 PM
I was curious to see the results of this survey as a “state of the art” (or science?) analysis. At this juncture, we consumers can pick from any of 6+ DNA commercial tests on the market, experimental admixture calculators at Gedmatch, regional Finestructure admixture tests previously only available to university researchers ("Living DNA"-People of British Isles study) & free health traits & ancestry tests offered by universities (Genes for Good) or scientists (DNA.Land).

I was 1 of the 2 thus far who selected "Semi-accurate - I somewhat know about my family history." :unsure: Therefore, perhaps I represent the other extreme of the testing pool than Anglecynn, or testers who know their family history back 100s of years. As an American of assumed British diaspora, I look to results like Anglecynn to see if I “look” within the norm of British posters or may have traces of other admixture picked up during Colonial era.

So feel free to have a “look” at what I see, as an American of assumed mostly British Isles ancestry, and judge for yourself: Am I still mostly British after all of these years in post-Colonial America on these tests? :nod: or :nono:

A few known (or widely assumed facts) about family heritage:

Family tree is documented partially across 3 lines to mid-1800s & 1 line fully to mid-1700s.
No known recent immigrants in America, e.g. late 19th century or later.
All surnames in family tree are common in Britain, with about 40% Scottish, 1 Irish & 1 anglicized from German to English)
Most immigration records point to settlers in mid-Atlantic to southern Colonial states in US.
Most common European ancestries in regions of family settlement in America: English, Scottish, Scots-Irish, Irish & German.
No recent family lines appeared to strongly identify with Old World ethnic groups except Scottish line with family book documented to 1100s, e.g. never heard terms “Celtic” or “Anglo-Saxon” and no participation in ethnic events such as Scottish Highlands games.


11-06-2016, 11:05 PM
I think Ancestry DNA did a pretty good job with its Ethnicity Estimate. Family Finder was less accurate but still in the ball park.

11-07-2016, 07:13 AM
I voted "semi-accurate". I have a pretty good knowledge of where my ancestors came from for a couple of hundred years.
Based on what I know I would expect them to be fairly typical of the Welsh Border Cluster, basically a mix of Welsh and A/S. Some results seem to broadly reflect this but the terms and groupings used by testing companies are, to me anyway, confusing - one which is particularly irritating is "British" and the lack of clarity of the time periods they are referring to. It seems some groups are so "close" they can't really distinguish between them, but give the impression they can.
I wish they could agree on a clearer more consistent system and admit their limitations, but I suppose that wouldn't sell tests. :) John