Sex determination is a long and sequential process, and despite the great progress in scientific research, the attribution of the definitive sex to a male or female sexual dimorphism at birth remains a mysterious and complex phenomenon. The investigations used for diagnosis and etiological research are numerous and molecular biology is also considered as a diagnostic tool that can be used for genetic counseling, especially in multiple family disorders. The frequency of congenital adrenal hyperplasia prompts systematic antenatal and neonatal screening. A multidisciplinary approach is essential in specialized centers in order to improve the quality of care and therapeutic decisions in the short and long term and to organize a psychological support network for children with an anomaly of sexual differentiation and their parents.