Björk, Dr Seuss, Whoopi Goldberg, Andy Warhol, Ellen MacArthur, Greta Gerwig, Andrea Bocelli, Hua Mulan ... these are men and women who all dared to be different. Boys will be boys and girls will be girls - or so the meaningless saying goes. Because what if you're a girl and you like cage fighting? Or you're a boy and you love ballet? And what if...