And finally, what about the experience of livestock breeders? Not only has strict brother and sister mating—the closest inbreeding possible—been carried on experimentally for twenty or twenty-five generations without bad results; but the history of practically every fine breed shows that inbreeding is largely responsible for its excellence.
The Ptolemies, who ruled Egypt for several centuries, wanted to keep the throne in the family, and hence practiced a system of intermating which has long been the classical evidence that consanguineous marriage is not necessarily followed by immediate evil effects. The following fragment of the genealogy of Cleopatra VII (mistress of Julius Cæsar and Marc Antony) is condensed from Weigall's Life and Times of Cleopatra (1914) and