@Dutchess_III “So everyone WILL show African genes but you’d have to go really far back for some, and the tests they do through Ancestry.com, etc. don’t go that far back.”
@Tropical_Willie said this way up here.
I have no idea whether all these ancestry sites use the same methods, or how far each of them go back, or even how they limit the number of generations they’re examining. I would have thought that any examination of the genome would reveal whatever genes are present, and that the hard part is associating specific genes with specific regions. To my mind, this kind of assessment is probably very polluted by poor probability estimates, and would depend on known pedigrees for specific families (relatively speaking, there can’t be too many of these available). I think the best use for these DNA tests is to find out how related a specific group of people are to each other. But reliability in terms of coming up with a specific region of origin based on the genome has to be kind of weak.
We do know that Africa was the region of origin for our entire species. Should we be able to see that in our genome? Maybe. But in the many generations of reproduction since Homo sapiens became a thing, could we not also have replaced every single gene in the genome several times over? That is the first question that comes to mind when I read your original question, @Dutchess_III, and my personal knowledge of this subject doesn’t allow me to answer it.