There seems to be a trend amongst 'western' geneticists, to cite third party (not of their own) sources to bolster theories that cannot be sufficiently explained by their own findings. This often leads to the referencing of sources that concern samples of geographic specifics, and possibly, sample sizes that are distinct from those of the research group doing the citing [of the foreign source], without full understanding of the archeological record and linguistic background of the sample subjects under study. A good example of this can be found in the 2009 study by Tishkoff et al. that was the topic of this blog in the same year, wherein the authors cite at least three different external sources on Fulani gene pool, concerning Y-DNA, mtDNA, and lactase persistence-affiliated T-13910 allele of the MCM6 gene, as means of securing support for a theory they envisioned from their limited data. For instance, they speculated that a section of their Fulani samples must have low to moderate levels of "European/Middle Eastern" ancestry, because there was some connection with the "European/Middle Eastern" cluster. Apparently their results were not sufficient enough to make that speculation conclusive, and so, compelled them to call on external sources as means to buttress their estimation of their results.