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Old 30th July 2017, 10:54 AM
Weasie46 Weasie46 is offline
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Join Date: Jul 2017
Posts: 1
Question % of Ethnic Origins passed to children

On May 5th I sent this message to FTDNA HelpDesk:
My origins are 70% Western Europe, 15% Scandinavian, 8% British and 5% East European. My husband is 55% East European, 45% Jewish. How is it possible for my son to be 20% Jewish (that makes sense) , 62% East European (this doesn't make sense) and 16% West and Central European. The implication is that he has only 16% autosomal DNA from me. If you throw in my 5% East European, he got 21% of his autosomal DNA from me. Shouldn't he have 50% from me which would mean less East European and some British, Scandinavian or more West/Central European. Please explain to me how his test results fit with those of his parents.

Since then I have received my daughter's results: 10% West/Central Europe, 20% Ashkenazi and 70% East European.

I received a reply finally on July 24th which basically said our tests are correct.

Could someone explain how the parents DNA is passed to their children?Obviously I am wrong in assuming it is roughly 50% from each parent since accordingly to the test results for my children, they received 80-90% of their ethnic origins from their father and 10-20% from their mother.

As a side note, the test results from My Heritage not surprisingly show a different breakdown of ethnic origins for all of us since I realize each company uses different reference populations. But what I find interesting that my children now have 40% of their ethnic origins similar to mine and 60% from their father.
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Old 30th July 2017, 11:37 AM
John McCoy John McCoy is offline
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Join Date: Nov 2013
Posts: 590
You are correct in thinking that an accurate admixture analysis should return consistent results for parents and their children. However, in the real world, the current tests obviously do not meet this criterion. The AncestryDNA "white paper" concerning the development of their current methodology discusses this problem and reports that they are getting better results for measures of consistency, but they don't actually report hard numbers. It would probably be difficult to do this, in any case, because different combinations of "reference groups" will likely be subject to different degrees of inconsistency.

I have feeling that the admixture scores are based on a weighted sum of scores for particular alleles at a large number of SNP's, and that those SNP's are not unique to any particular ethnic group. Consequently, I imagine that some SNP alleles are used in the scoring of more than one ethnic group, and therefore it might happen that some of the "eastern European" SNP alleles that occur in other ethnic groups came from one parent (and not necessarily from actual "eastern European" ancestors), and the rest from the other parent, but when they are found together in one individual, they result in an inflated score.

There are statistical methodologies that might address this problem, but the more significant issue may be that the "reference groups" (samples from modern, and probably still living individuals) are not large enough nor comprehensive enough to capture the genetic diversity of the "ethnic groups" they are supposed to represent.
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