Keeping it out of the family

If you marry your sister or brother, as the Pharaohs did, your offspring may inherit disorders.

Even wild creatures avoid mating with their kin. Their precautions tend to be simple ones but, according to recent research in Benidorm, storm petrels (above) have a sophisticated way of avoiding incest.

Charles Darwin married Emma Wedgwood, his first cousin. Anxious by disposition and a life-long hypochondriac, the great naturalist worried about possible consequences for his children. Fretting about things outside our control is futile but, in Darwin’s case, it was beneficial. Worries about ‘consanguinity’ focused his attention on the nature of inheritance; how traits are passed from one generation to the next became central to his theory of natural selection.