"European Americans" are not homogenous
A new paper in PLoS ONE, Genetic Population Structure Analysis in New Hampshire Reveals Eastern European Ancestry, tells us little that wasn't already obvious: genetic distinctions can be drawn among "white" Americans. Unfortunately, only 960 SNPs, mostly on "suspected cancer susceptibility genes", are used for the structure analysis, and most of the clusters reported (for example, Jewish-French Canadian-Candian Indian) don't seem terribly meaningful. "Eastern European ancestry" is mentioned in the title only because "Finnish and Russian/Polish/Lithuanian ancestries were most notably found to be associated with genetic substructure" in this data set. As we've seen repeatedly, with more markers, clear and meaningful genetic substructure is apparent throughout Europe and across various European ancestry groups in the US.