This chapter focuses on the management of knowing and unknowing in the life narratives of Dutch women with XY sex chromosomes. It examines how caretakers were supposed to handle contingent knowledge on intersex conditions within an oppositional gender classification cautiously. The chapter discusses the medical power/knowledge asymmetry between physicians and patients that is used to make persons with intersex conditions fit in the hetero-normative gender binary. It then explores how this medical normalization is re-enacted or subverted in life-narratives of Dutch women with XY sex chromosomes. The chapter shows that gendered assumptions have consistently controlled knowledge and informed the medical ethical conviction that unknowing was better than knowing. A person with XY sex chromosomes can show hypertension, a shortage of stress hormones, hypoglycemia and atypical sex anatomy: under-masculinization and female phenotype including spontaneous breast development. The chapter provides a brief history of the categorization of 'Testicular Feminization' or 'Male Pseudo Hermaphroditism'.