The operative word in this discussion is "rough"! No matter how carefully a "reference population" is constructed, assumptions have to be made about the ancestry of the people who are sampled. There can be no guarantee that the samples "represent" the populations of particular places in particular historical times. Nor is there any guarantee that your particular ancestors who came from those places were "typical" of those places and times!

You can also see that there are many different versions of software tools intended to estimate ethnic ancestry. The fact that they produce different results is significant. If most of them happen to agree on the general outlines of your ancestry, that's about the best you can hope for.

John McCoy
(RealMac@aol.com)