During the last several decades science has shown that the development of biological sex is complex. It consists of the genotype, defined as the sex chromosomes of an individual and the phenotype, defined as the observed physical characteristics of an individual's sexual anatomy. The phenotype is what is observed at birth that causes others to say. "It's a girl" or "it's a boy. Sexual differentiation in the human embryo is a developmental process. In the early embryo, two primordial (or early) anatomical structures are found, one male, the other female. Every embryo has both structures. In an intricate interplay of genes, growth factors and hormones, one of the structures is developed while the other regresses. Because of this complex interplay, sexual development unfolds in a continuum of steps. There may be variations from the typical interplay of genes and hormones and these alterations lead to human diversity. These videos foster a deeper understanding of identity and encourage acceptance and curiosity in what it truly means to be human.