Once upon a time, there was sex. And it was obvious. The difference between female and male genitalia should extend to female and male ways of being in the world. But anatomy is not the whole story. In the sixties, physicians themselves began to make a distinction between the sexed body and the lived body. We feel more or less feminine, more or less masculine. We learn to become what is expected of us. We accept or reject the sex we were assigned at birth. And that is gender. We should not be afraid of this word. It helps us study attitudes, roles, and identities. It reveals inequalities in laws, morals, and social representations. It opens our eyes to patriarchal power, male violence, and global misogyny. All of this is both historical and normative knowledge. In this seminar, I present a synthetic genealogy of the concept of gender (in the plural). I argue that a person's right to transform their gender expressions and embodied identifications is essential to the ongoing, unending task of the neomodern project.