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Ok, I have read a bunch, looked at posts and read articles. Help me understand the whole percentages thing regarding admixture/autosomal DNA results. So based on prior posts on the forum, if you are 3% of something that is likely from a 3/4 times great grandparent or 200 or so years ago. If you are 25% of something that means more recent or no? Or does it mean that through the random recombination of DNA, that one just happens to have 25% of whatever even if their mother or father is not 50% of whatever?
If you have 25% of some ethnicity, shouldn't you have a recent known history of it? Thanks
Ok, I have read a bunch, looked at posts and read articles. Help me understand the whole percentages thing regarding admixture/autosomal DNA results. So based on prior posts on the forum, if you are 3% of something that is likely from a 3/4 times great grandparent or 200 or so years ago. If you are 25% of something that means more recent or no? Or does it mean that through the random recombination of DNA, that one just happens to have 25% of whatever even if their mother or father is not 50% of whatever?
If you have 25% of some ethnicity, shouldn't you have a recent known history of it? Thanks
The admixture results are based on genetic markers known to be associated with certain geographical regions.
Those markers can come from any ancestor. The percentages do not tell you which one(s). Your 25% is more likely to come from multiple ancestors, not just one. So the 25% might all come from either mom or dad or a fraction of that 25% of varying size from both.
If you go back further and further to distant ancestors, you will eventually have some from which you have inherited no DNA at all. That is why those who are interested in Native American DNA to confirm family stories may be able to show it is there if it shows up in their admixture but cannot be sure a NA ancestor never existed just because there is no known NA marker present. There is also the problem that some NA populations have no DNA submitted to compare to.
Larger percentages will indeed imply more recent admixture, which you might be able to find if you do the search for the actual ancestors. However, the 25% still may come from contributions from two or more individuals, not just one.
Those markers can come from any ancestor. The percentages do not tell you which one(s). Your 25% is more likely to come from multiple ancestors, not just one. So the 25% might all come from either mom or dad or a fraction of that 25% of varying size from both.
If you go back further and further to distant ancestors, you will eventually have some from which you have inherited no DNA at all. That is why those who are interested in Native American DNA to confirm family stories may be able to show it is there if it shows up in their admixture but cannot be sure a NA ancestor never existed just because there is no known NA marker present. There is also the problem that some NA populations have no DNA submitted to compare to.
Larger percentages will indeed imply more recent admixture, which you might be able to find if you do the search for the actual ancestors. However, the 25% still may come from contributions from two or more individuals, not just one.
Thanks for your helpful response.
09-22-2015, 08:12 PM
2K5Gx2km
n/a posts
Quote:
Originally Posted by oldhousegirl
Thanks for your helpful response.
This is also why it is helpful to have segment lengths when looking at chromosomes (23&Me has this). The longer the segment the more recent because of recombination at each generation.
This is also why it is helpful to have segment lengths when looking at chromosomes (23&Me has this). The longer the segment the more recent because of recombination at each generation.
Yes, unfortunately I don't have the segment lengths. My test was given as a gift from Ancestry. That would have been great to see, but I am still thrilled with what I have!
Yes, unfortunately I don't have the segment lengths. My test was given as a gift from Ancestry. That would have been great to see, but I am still thrilled with what I have!
You can import your results to gedmatch.com for free (they have instructions for downloading your dna data from Ancestry) and from there you can look at segments... Once it's imported you'll want to:
1) Click on the link "Admixture (heritage)"
2) Choose a data set in the drop down... A good option is Eurogenes
3) Switch the radio button to "Chromosome Painting"
4) Enter the kit number, this is given after you import and should be located on the gedmatch.com homepage (after you import)
5) Wait
Then it will paint each ethnicity across each Chromosome, it will take a couple to a few seconds for each Chromosome to appear.
From that point by eye you can get a general idea how big an ethnic segment is... beyond that you can convert the numbers given as a guide into a more concrete value that you can use to determine if it's legitimate or not (I'd reserver that step for later, consider it an "advanced" step
If you're talking about different ethnicities within a continent, then do not expect the company to be able to figure that out accurately. For example, Ancestry says I am 30% Scandinavian, but I do not have even 1% of that ethnicity on paper. 23andMe says I have 2% Scandinavian ancestry, but I think even that is a mistake. Many different populations within Europe (or Africa, or the Americas) are very difficult to distinguish from others. Now if your results are saying you are 25% Subsaharan African and 75% European, then that would be fairly accurate. The two are easily distinguishable by Ancestry.
If you're talking about different ethnicities within a continent, then do not expect the company to be able to figure that out accurately. For example, Ancestry says I am 30% Scandinavian, but I do not have even 1% of that ethnicity on paper. 23andMe says I have 2% Scandinavian ancestry, but I think even that is a mistake. Many different populations within Europe (or Africa, or the Americas) are very difficult to distinguish from others. Now if your results are saying you are 25% Subsaharan African and 75% European, then that would be fairly accurate. The two are easily distinguishable by Ancestry.
That's exactly it, my known (paper) vs. their estimates. Thank you.
where ever people live and they move on, they will be some that will stay in that area, so by comparing your dna with people in that area in today time they can trace where that dna been. so by saying 10% or 30% they are comparing with others that are alive today or at least when the study started.
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