DSD for "Differences of Sex Development" or "Sexual Differences Development" refers to situations where chromosomal, gonadal or anatomical sex is atypical. DSD 46,XX are mainly represented by congenital adrenal hyperplasia (HCS) and are not a diagnostic issue. DSD 46,XY involve genes for the determination and differenciation of the bipotential gonad, making sometimes difficult the choice of sex at birth. They remain without diagnosis in about half of the cases, despite the new genetic techniques (exome, NGS). The management of DSD is complex as well as are the long-term consequences, particularly in terms of options for medical or surgical treatments, fertility and quality of life of patients that should be discussed. This review describes the main causes of DSD and the recent issues of their clinical management. It addresses the difficult question of identity of these patients, in a society that leaves no place for difference.