Prince William may have little to no Indian ancestry

Credit: Robert PayneThe British media is blowing up today about Prince William's Indian ancestry. Here's a representative headline: Hunt is on in Gujarat for a distant cousin who shares Prince William’s Indian blood. The science here is straightforward. Apparently some British researchers found third cousins of Lady Diana Spencer. These individuals, like Diana, are descended from a woman named Eliza Kewark. This woman, William's great, great, great, great, great grandmother was an ethnic Armenian who was resident in India. She was also the housekeeper of William's ancestor Theodore Forbes, a Scottish merchant. At some point he sent his children by this woman to be educated in England, and there William's ancestress married into native British lineages. Since Diana's cousins share the same unbroken matriline as she does they by definition share an mtDNA lineage. As it happens these individuals carry haplgroup R30b, a very rare lineage found only in South Asia. But that's not all. Diana's cousins also are 0.3% and 0.8% South Asian on their autosomal genome. The intersection of these two facts does convince me that William's genealogical ancestress, Eliza Kewark, did have South Asian ancestry (not totally surprising even in notionally ethnically distinct groups like Armenians or Parsis who have been long resident in India). But please note that I said genealogical ancestress. Observe the large variance in ancestry of Diana's two third cousins presumably derived from Eliza Kewark (though there is always the chance that these segments come from different South Asian ancestors, the typically South Asian mtDNA match across the two reduces the probability of that being the answer in this case). Beyond eight generations the chance of a