Ethnic percentage relevance

[Lassie]

I have seen some comments on here where people have around 10% of an ethnic group and have almost dismissed this as not very recent dna.

I have 8% African the rest British. GED match confirmed. The African is from a great grandfather of my kit subject. He is unknown NPE in Australia confirmed through African yDNA along that line. The African person is believed to be a seaman from the ships that bought the cargo and colonists here as there were very few Africans in Australia then. He is the only reason I am doing DNA testing in order to find out more about him. The sections of African on the chromosomes (from Dr McDonald) I am aware of and they consist of 5 large segments 30 to 60 Mb as well as a number of other segments over 10Mb long. I think the size of the sections are relevant.

Am I right in assuming he was 50 to 100 percent African? This is important as I may be able to figure out who he was.

[Draceana]

Hello,

I sent you a private message. I have some ideas

Thanks!

[Lassie]

Ethnic Percentage relevance

The assumption of one of my unknown ancestor is 50 to 100% African is based on the African DNA halving each generation. So if he is three generations back from the test subject (8%) then he would have around 64% African DNA. He is the only African the rest of ggggrandparents are all known British and yDNA confirms the paternal line is African haplogroup.

Is this a fair assumption??

[jbarry6899]

Ethnic percentage relevance

It's important to note that the percentages given in MyOrigins or any BGA calculator are not the percent of your ancestors of a particular ethnicity. They are a statistical artifact derived using a process called principal component analysis. Simplified, the figures represent the share of the variance in your results, compared to a reference standard, that are explained by comparison to the various sample groups. So, for example, my 76% European Coastal Islands does not mean that 76% or my ancestors came from that region; it only means that 76% of the variance in my results can be explained by comparison with that reference group.

The concepts are related, but not the same, and thus the percentages should not be taken literally.

The White Paper describing the methodology is here:

https://www.familytreedna.com/learn/...s-methodology/

Jim

[Kathleen Carrow]

It's important to note that the percentages given in MyOrigins or any BGA calculator are not the percent of your ancestors of a particular ethnicity. They are a statistical artifact derived using a process called principal component analysis. Simplified, the figures represent the share of the variance in your results, compared to a reference standard, that are explained by comparison to the various sample groups. So, for example, my 76% European Coastal Islands does not mean that 76% or my ancestors came from that region; it only means that 76% of the variance in my results can be explained by comparison with that reference group.

The concepts are related, but not the same, and thus the percentages should not be taken literally.


Jim

Thank you.. That helped