Why do people stop growing taller after 21 years old?
Human height growth doesn't last forever. At what point does it end? It all depends on the condition that your plates are growing. The growth plates are cartilage zones that are located at the end of long bone (the femur and tibia, for example). They are the place where new bone is formed to increase the length of our limbs and ultimately , increase our height.
When these growth plates begin to become amorphous or completely fused and stop growing, individuals cannot get more taller. See more at https://howtogrowtaller.com/he....ight-increase-after-