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MitchellSince1893
02-14-2014, 12:04 AM
I'm looking for some enlightenment from some autosomal admixture experts.

My parents and I have tested with 23andme. When I use the "Countries of Ancestry" tool at 23andme or use some of the admixture tools on gedmatch, I often come out more German than either parent.

On 23andme's "ancestry composition" tool I'm 11.5% German-French on speculative mode, My mother is less than .1% and my father is .2% German and French

I originally thought it was because I just happened to inherit a disproportionate amount of German dna both my parents.

However, as seen in this picture from the 23andme Countries of Ancestry tool, I have "German" sections of my chromosomes (green ovals) that don't match either my father (blue ovals) or mother (pink ovals).

As I mentioned I see this same result (I'm more German than either parent) using other gedmatch autosomal tools so it's not just a 23andme thing.


Is this result a limitation of the autosomal algorithms e.g. the way my parents dna mixed makes me appear to be more german when in fact I'm not or is there something else going on?

Using a simplistic example to explain what I'm wondering: Say a father is 100% German and a mother is 100% Irish. Even though the kid has no English ancestry, would he appear more English than either parent as the English are autosomally in between Irish and Germans? Is that what's going on here?

Thanks in advance for helping understand these results.

MitchellSince1893
10-04-2015, 04:04 PM
A year and a half later I think I've figured out why I'm more German than either parent, and in general, why your results are often not in between your parents percentages on various admixture tools.

The graphics below are a simplistic illustration of how this could happen.

Sticking with my German example in the original post:

Your father inherited German ancestry from his mother or father or combination of both, and it makes up 5% of his overall ancestry. In this example he inherits all his German ancestry from his mother (shown in yellow on chromsome 1).

Your mother inherited German ancestry from her mother or father or combination of both, and it makes up 4% of her overall ancestry In this example she inherits all her German ancestry from her father (shown in yellow on chromosome 7...slide says 6 but it should say 7).

You just happen to inherit both of your parents' German dna segments and thus you end up with 9% German ancestry (shown on the 3rd image below).

6163

6164

6165

randwulf
10-04-2015, 05:53 PM
I have a similar situation in that I am always a little more "Mediterranean" than either of my parents. I picked a few spots on my chromosome paintings where I was heavily Mediterranean and compared to my parents. There is a tendency on these that I am getting that from both parents to the exclusion, usually, of something north European.