At what amount would admixture be visible?

[Sam Ryan]

Say someone has a 3rd or 4th great-grandfather from Portugal but the rest of their ancestors are from the British Isles. They wouldn't have more than 2 percent Portuguese admixture and the rest from NW Europe. Is 2 to 3 percent of something visible or would it be impossible to discern, drowned out by all the other influences?
Any real-world examples of a 2 percent admixture being visible?

[Leto]

2, 12 or even 20 percent Portuguese in a British person will not be visible because it's also a European ethnicity. Non-Caucasoid races are a different story, though 2-3% is (normally) too small an amount even for that type of ancestry.

[mitalit]

2% is very little. But a great-grandparent (12%) is probably visible

[Flashball]

Doesn't work like that...


In genetics, reasoning like this: "from 3 to 25% is too low, so extra-European genetic variants will not be expressed" is not correct.

This would be rather exact to say : from 3 to 25%, the genetic variants are always present in the genome, however the level of expression of these non-European genetic variants (old or recent) is variable according the percentage.

For example, the rate of ancient North African among Galicians is at the highest of 11% and 2.6% (I believe) among Catalans, so it must be understood that there is more probability of expression of genetic variants non-euro in a Galician village with 10% old North African than in a Catalan village with 2% old North African... but that does not mean that it does not exist among Catalans with 2%, you have to see everything this in terms of "probability of expression of genetic variants", not so much in terms of "11% is low, so no chance of expression of genetic variants", because it is incorrect and unscientific reasoning.

[Petalpusher]

It's indeed more a probability of expression, visible expression i would add in that case. Even 1% of admixture out of the typically few thousand of snps tested, translate into a lot of genes overall that could peak in a very different ethnicity. Statistically some features more prevalent in a particular group could show up even at very low level of admixture but are decreasingly likely to be dominant in many visible ones, as much as in the invisible ones such as complex organs like the brain which requires much more genes than anything visible in the phenotype. People are obsessed with visible features when talking about genes, admixture and so on but 1/3 of all our genes expressed and active serve the brain alone. This is the highest proportion of genes expressed in any part of the body.


People with the same or very similar admixture don't all look the same or even siblings can look quite different and more important have different personality, only twins do look the same and think the same (some striking studies about this), as they have an identical gene expression out of the same pool.

[RareNightmare]

Porutgese people are europeans and it is 1/50th. Also, if you took a full Portuguese person and a full british person stripped them down and asked a random non anthrotard person to guess their country of origin/ethnicity and if they were the same, they probably couldn't discern the two especially if you grabbed someone who was as much as a quarter Portuguese and then someone who was a full blooded brit. Call me retarded, but I wasn't able to tell that even Tom Hanks was half portuguese. gettyimages-1257937597.jpg

[Roy]

2, 12 or even 20 percent Portuguese in a British person will not be visible because it's also a European ethnicity. Non-Caucasoid races are a different story, though 2-3% is (normally) too small an amount even for that type of ancestry.

Somehow though we've seen Hungarians and Romanians with 1-3% of Asian DNA which imho shows up subtly in them phenotypically. And don't forget a Mongolian spot on newborns that show up even on those with a very minimal Asian input in their DNA.

https://en.wikipedia.org/wiki/Mongolian_spot

[Mr.G]

Any amount can theoretically be visible. Question should be, what amount of admix is consistently visible. For that I would say 12-25% range.

[Zoro]

Somehow though we've seen Hungarians and Romanians with 1-3% of Asian DNA which imho shows up subtly in them phenotypically. And don't forget a Mongolian spot on newborns that show up even on those with a very minimal Asian input in their DNA.

https://en.wikipedia.org/wiki/Mongolian_spot

You wouldn’t see Asian facial features if it was only 1-3%. This number is meaningless because it doesn’t tell you how much older and more recent total Asian DNA they have. All the number says is they have 1-3% above the Romanian or E. european references. What they don’t tell you is how much E. Asian older and more recent E. Asian those Romanian and E. European references themselves have !!

[Roy]

You wouldn’t see Asian facial features if it was only 1-3%. This number is meaningless because it doesn’t tell you how much older and more recent total Asian DNA they have. All the number says is they have 1-3% above the Romanian or E. european references. What they don’t tell you is how much E. Asian older and more recent E. Asian those Romanian and E. European references themselves have !!

So these tests are faulty in their design?