Karen Horney's critique of Freud's theory of female development suggests that much theory and research in psychology is androcentric, and calls for the elimination of biases. This point is questioned, and the posit that scientific knowledge does not answer the question of what makes a person either female or male is explored. Biological, psychological, and sociological differences overlap genders, and the inconsistencies are discussed. The biological attempts at differentiation of sex are unsuccessful, whether through hormones, chromosomes, sexual organs, or whatever. The constancy of gender identity is evident in the discussion of transexualism. The example of biological attribution of gender is considered, while the "ultimate" criteria remains elusive. Gender, in all of its manifestations, including the physical, must be seen as a social construction. (LS)