Final answer:
The process of learning what it means to be male or female begins at birth through socialization into certain gender roles. Additionally, the development of sexual organs and reproductive systems in the embryo determines biological sex.
Step-by-step explanation:
The process of learning what it means to be male or female begins at birth because children are socialized into certain gender roles that are typically linked to their biological sex. This socialization process reinforces the gender binary system, where male and female are the two categorized genders. Additionally, the development of sexual organs and reproductive systems starts in the embryo, with males being exposed to a cascade of factors initiated by the SRY gene on the Y chromosome, which leads to the development of male reproductive organs.