The world has ~8 billion people. The mutation rate is ~10^-8 per base pair, so every base pair has mutated ~160 times in the past generation alone. Thus, every single (non-lethal) base pair mutation will be present in every large human grouping. 2/n

An allele currently found only in European ancestry sequences will be present in India many times over for example. Rapid population growth means that there’s a vast reservoir of rare alleles within all human “ancestry groups". No rare allele will be specific to one of them. 3/n