“Marrying cousins was astoundingly common into the nineteenth century, and nowhere is this better illustrated than with the Darwins and their cousins the Wedgwoods (of pottery fame). Charles married his first cousin Emma Wedgwood, daughter of his beloved Uncle Josiah. Darwin's sister Caroline, meanwhile, married Josiah Wedgwood III, Emma's brother and the Darwin siblings' joint first cousin. Another of Emma's brothers, Henry, married not a Darwin but a first cousin from another branch of his own Wedgwood family, adding another strand to the family's wondrously convoluted genetics. Finally, Charles Langton, who was not related to either family, first married Charlotte Wedgwood, another daughter of Josiah and cousin of Charles, and then upon Charlotte's death married Darwin's sister Emily, thus becoming, it seems, his sister-in-law's sister-in-law's husband and raising the possibility that any children of the union would be their own first cousins.”