We are born without any, or with very little. We grow up resisting attempts to wash it, tame it or cut it, but by the time we are adults most of us have developed a certain attachment to our hair. It’s personal. Other people’s hair is another matter. We lovingly stroke the hair of dogs and cats, wear clothing made from the hair of sheep or rabbits, but the sight of a stranger’s hair on our clothes, in the shower or – heaven forbid – in our food provokes disgust.