Final answer:
At birth, male and female inflnts are distinguished by reproductive organs, which are genitalia used in the reproductive process.
Step-by-step explanation:
At birth, male and female infants are distinguished by their genitalia, which are reproductive organs used in the reproductive process. Sexual differentiation, which includes the development of these reproductive structures, does not begin until the fetal period, between weeks 9-12. Initially, embryonic males and females have bipotential gonads that are morphologically identical and can develop into either male or female sexual organs.
The presence or absence of testosterone leads to the development of these organs into either male or female genitalia. Males will develop testes and a pen/is, while females will develop ovaries, a cli/toris, and labia. These structures are homologous, meaning they develop from the same embryonic tissues.