What evidence did Darwin have (close to home) of the negative impact of marrying a cousin?

illness in his son

death of children

smaller children

infertility of children

crippled child

1 answer

One piece of evidence that Darwin had close to home of the negative impact of marrying a cousin was the illness in his own son. Darwin's son, Charles Waring Darwin, suffered from various health issues that were believed to be a result of the close genetic relationship between Darwin and his wife, Emma Wedgwood, who were first cousins. This led Darwin to express concerns about the potential negative effects of consanguineous marriages, or marriages between close relatives, in his work on heredity and evolution.