Well, we do have Cheryls on this list, but none have posted recently. So that's why I asked.
Yes, the math is right. Some 100% Portuguese who marries say, an British Isles type, will have a kid who is 50%. And if they continue to marry the British Isles (or whatever) type, it's 25% (1/4), 12.5% (1/8), 6.25% (1/16).
So when does it wash out? I guess of the ethnicity ESTIMATES? I think it's too early to say. The companies are still trying to get descent population samples that represent a really good cross-section of each population. That has not happened yet.
Here's my 50% dad at Ancestry:
Here's my 50% dad on My Heritage:
Here's my 50% dad on FTDNA:
And lastly, here's my 50% dad on Living DNA (I tested him there to see how they would sort out his British Isles half, because he really is half British Isles with a smidge of German thrown in):
So my dad 50% dad varies with 33%, 37%, 25% and 24%. I understand that the companies will probably never read his DNA anywhere close to 50%. His DNA is Frankish (so says FTDNA). You can look up the Franks and Roman Empire in Wikipedia for the history. I also know some French settled on Sao Miguel too. Although I haven't found that ancestor on paper, it seems that the French algorithm loves to gobble up and over read that part of my dad's DNA too (well, on the companies that have it).
Now, here's 25% me at Ancestry:
Yeah, I don't see any Portuguese there either.
I did not test on My Heritage (or transfer). But I tested on 23 and Me instead (I'm still 25% on paper):
Here's me on FTDNA:
So with the 3 companies that I've tested or transferred, I've got 0%, 25% or 33%. And I'm 25% on paper. LOL My mom is NOT Portuguese. She's midwestern, yee-haw hillbilly. And the results are closer to being accurate on me, but not so much on my dad. However, my dad is a descendant of double 1st cousins, so he could have inherited something (the French?) that is being over read.
So I go by the DNA matches. There are people in Australia whose immigrant arrived in the mid-1800s. There are people in Brazil whose immigrant arrived in the mid-1700s. Those people do show matches to others who are 100% Azorean. So it hasn't washed out. It's still there. I don't care what the ethnicity ESTIMATES say, I only care if they can make a connection.
Hope this helps, Cheri