Intersexuality questions how human gender definition occurs. As a baby is born, a sex, boy or girl, is assigned through genital observation. However, the simplicity to assign the gender disappears when, as the genitals are observed, their conformation is not clear. Genitals are ambiguous when their appearance imposes difficulties, or even an impossibility to assign a sex to a child. This is the case for children born with some degree of deformity or any Sexual Differentiation Disorders (SDD). Such fact places a strain, both on the parents and on those who will assist the child. The complexity of the problem demands that the child be assisted by an interdisciplinary team composed of a pediatrician, an endocrinologist, a surgeon and a psychologist in addition to a team of diagnostics experts. A study is undertaken in order to understand what caused the Genital Ambiguity (GA) and, therefore, make sex definition possible. When the SDD diagnosis is established early in life, it can cause severe angst on the parents or even the family. That is because it is the family who will be held responsible for what happens to the child. The name choice and the civil registry is the parents’ responsibility. They must make a choice. The parents decide if there will be an investigation in order to make the biological sex clear, or if they will allow the child to grow so that they can define their own sex, based on the assumption that nature itself may decide the path towards sexual clarity. Although possible, that is a perilous path to follow, since biology has already given hints that something has happened that prevented the sexual identification already at birth. The article deals with the main discoveries and psychoanalytic concepts in relation to sexual constitution and its workings in order to clarify the question that has guided and accompanied us along the way: does sexual ambiguity interfere in the assumption of sex made by the subject? Clinical medicine teaches us how the subjects have answered the question: Am I a boy or a girl?