HapMap
Dienekes comments on the paper which showed genetic substructure among a set of Sardinian villages:
The take-home lesson is that wherever gene flow is impeded, no matter how geographically close, population differentiation can be recovered with dense autosomal genotype data.
Really fine-scale ancestry analysis is now possible; I suspect that a combination of geography, religion, social class, language, and ethnic identification will be found to be predictive of a person's broad genetic makeup and vice versa. But, to discover these correlations, a large-scale collection of genotypic data is…
Geographical Affinities of the HapMap Samples:
The CHB and JPT are readily distinguished from one another with both autosomal and Y-chromosomal markers, and results obtained after combining them into a single sample should be interpreted with caution. The CEU are better described as being of Western European ancestry than of Northern European ancestry as often reported. Both the CHB and CEU show subtle but detectable signs of admixture. Thus the YRI and JPT samples are well-suited to standard population-genetic studies, but the CHB and CEU less so.