Since the advent of cheap DNA tests, several companies have sprung up which will tell you ancestral origins according to your DNA.
Where in the world are you from?
Find out where your DNA comes from around the world. Your DNA can tell you where your ancestors lived more than 500 years ago. See a percentage breakdown by region, including eastern Asia, Sub-Saharan Africa, Europe and more. We look at 31 populations worldwide, and we will continue to refine your results as our database grows.
AncestryDNA makes similar claims
Nigerian? Scandinavian? What are you?
AncestryDNA can estimate your origins to 26 ethnic regions, 9 in Africa alone—more than anyone else. And we've got Europe covered 9 ways.
Reading through their advertising claims, I am having a hard time determining what exactly it means to be 72.3% Northern European, or 24% Ghana/Ivory Coast. At what point in history was there an archetypal group of people who were 100% Ivory Coast? My historical knowledge of human migration and population growth is pretty spotty, but I am under the impression that it was a very messy process. Their site has a veneer of science, but is clearly targeted at a lay audience. This question could be improved by finding a scientific discussion of what the company's scientists think their ancestry reports mean.
I am skeptical of the claims partly because they seem difficult to falsify. If a DNA test says that my ancestors are 19% asian, who can argue with that? The ancestors in question are dead.
What evidence shows that the DNA tests from 23andMe and AncestryDNA provide accurate and meaningful results? Is this evidence sufficient to justify their claims?
Note: I have to tip my hat to @Statsanalyst who originally asked a similar question that lacked a specific answerable claim.