Here's why:

* Endocrine system: The testes and ovaries produce hormones that regulate various bodily functions.

* Testes: Produce testosterone, which is responsible for male sexual development and characteristics.

* Ovaries: Produce estrogen and progesterone, which are crucial for female sexual development, menstruation, and pregnancy.

* Reproductive system: These organs are the primary producers of gametes (sperm in the testes, eggs in the ovaries), essential for sexual reproduction.