Mermaids, a gender-identity support group, says that transgendered boys may prefer to play with make-up and dressing-up clothes, rather than traditional male toys. And girls may insist on cutting their hair short, wearing boys’ clothes (including underwear) and playing rowdy games. Many aggressive or rowdy girls have been mistakenly diagnosed with behavioural difficulties. But transgendered children demonstrate a greater degree of cross-gender identification than their peers.

A Mermaids spokeswoman said: “Some transgendered children don’t know if they’re a girl or a boy. They just know how they like to behave. Others say, I know I’m a little boy, but I want to grow up to be a girl.”

If a child’s behaviour becomes extreme, he or she should be taken to their GP. The GP should refer the child to specialists in gender-identity, who do psychological tests, resulting in a diagnosis. But this diagnosis is not static: it merely indicates that the child is experiencing a form of gender variance. This could evolve in different ways in later life.