Right! But if you only go back ten generations, you have 512 ancestors. Direct paternal and direct maternal only takes care of two of them. How about the other 510? And ten generations is not "deep ancestry." In short order you get into the millions of ancestors, more, in fact, than the total population of the earth. Oops! Do I smell an incest scandal here?
The way I read this article, they don't claim they're going to give you information on all of the 512 ancestors you've mentioned in your example -- they'll just give general information on one or two ancestors.
So someone can argue that the test won't provide all the information they might like to have. But they can't argue that someone with a mixed-race background is going to get results that are distorted or imprecise. Do I have that right?
This is an excellent map drawn from the DNA studies of professor Stephen Oppenheimer, It was privately funded by The Bradshaw Foundation.
The Journey Of Mankind (The Peopleing Of The World)
Note the first humans out of Africa failed...and, he places the first Americans at Meadowcroft 25,000 years ago. (Etc)