@ChristiJunior @c It's usually due to incredibly rare genetic disorders (0.02-0.05% of the US populace) that cause a neonate's genitalia to be "ambiguous" at birth. Androgen insensitivity syndrome (XY sex chromosomes but kid looks female) is one of the most frequently mentioned ones

They used to be called "hermaphrodites" but they don't really have a fully functioning set of male and female sex organs at all. Most are sterile, and the human body tends to default to female in the case of genetic anomalies.