It is an article of fashionable faith that genetic differences in sex are meaningless and malleable, but genetic differences in race are so profound and meaningful that they must not be tinkered with at all, even though race, we are told, is a ‘social construct’. Hence it is positively progressive to sneak a cheeky penis into a women’s changing room, providing the penis is attached to a ‘trans woman’. But it was despicably racist of the disgraced professor Jessica Krug, who was born white and Jewish, to have masqueraded as a woman of color.