When is sexual differentiation of the human reproductive system completed?

While the genetic sex of an individual is determined at the moment of fertilization, the process of sexual differentiation occurs in stages throughout development.

During the first eight weeks of gestation, the human embryo remains in a neutral or indifferent stage, where its sex cannot be determined by external observation. Following this, the gonads begin to differentiate, and the Wolffian and Müllerian ducts develop or atrophy based on hormonal influences. By birth, the reproductive organs are anatomically developed and in their adult positions, though they are not yet functional.12

Sexual differentiation is ultimately completed at puberty, the stage at which the reproductive system in both men and women reaches maturity and becomes fully functional.2