いとこ婚
There was a notable history of intermarriage within the family. During the period being discussed, Josiah Wedgwood married his third cousin Sarah Wedgwood; Charles Darwin married his first cousin Emma Wedgwood; his sister, Caroline Darwin, married Emma's brother (and Caroline's first cousin), Josiah Wedgwood III. There were other instances of cousin marriage as well. Cousin marriage was not uncommon in Britain during the 19th century though why is debated: poorer communications, keeping wealth within the family, more opportunity of evaluating a relative of the opposite sex as a suitable marriage partner (unmarried young women of the upper and upper middle classes were closely chaperoned when meeting men outside the family during the 19th century), more security for the woman as she would not be leaving her family (though legal rights for married women increased during the century, as a rule her property became his and she had little legal recourse if he chose to abuse her).