- Darwin's maternal grandfather, Josiah Wedgwood, the founder of the pottery dynasty, had married his own third cousin, Sarah, and had eight children.
- The couple's eldest daughter, Susannah Wedgwood, married Robert Darwin, her cousin. Charles was their child.
- Meanwhile, Josiah and Sarah's second eldest son, also Josiah, had nine children, of whom four, including Emma, married first cousins.
Moore, who is about to publish a research paper on Darwin, said: "The results of this unintended experiment in close-cousin breeding are striking — 26 children were born from these first-cousin marriages, yet 19 of the offspring did not reproduce. Five died prematurely, five were unmarried and considered deficient, and nine married without issue.
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