is there some sort of cutoff point where scientists decided “everyone in Ireland 100,000 years ago will be considered 100% Irish”?
In: 12
Those DNA ancestry tests aren’t exactly “scientific”. Basically the way they work is that they have a database of people for whom they have both DNA test results and some kind of statement about where they think their ancestors are from. They compare your results to the people on the database and give you numerical scores based on how similar your DNA is to those whose ancestors are supposedly from a given region. Different tests can give you quite different results, because they use different databases and different methodologies.
It wouldn’t be possible to have a hard cutoff point at, say 100 thousand years ago, or even 1 thousand years, because (a) there have been mutations since then and (b) it’s hard to trace population genetics that far back with much certainty, as almost all of the available DNA data is recent.
There are serious scientific studies of population genetics too, but they tend to focus on the distribution of specific genes instead of more nebulous concepts like “African DNA”.
Latest Answers