Men are taller than women because of sexual dimorphism. This is the scientific term used to describe the biological differences between males and females in the same species. Sexual dimorphism varies between species and in the case of humans, men are, on average, taller than women.
There is also a genetic reason for the height difference between men and women. Medical studies have found that there is a genetic variant in the X chromosome that can have an important role in determining the height of a man or woman.
Women have two X chromosomes, which means they are at much higher risk of being susceptible to this genetic variant. Researchers have found that a gene that is involved with cartilage development can be altered because of the genetic variant that is present in the X chromosome. Because they sometimes lack the ability to develop their bones and cartilage, women end up being much shorter than men.
Studies have also found that shorter women tend to have more children than women who are tall, while men who are considered average height tend to reproduce more than their shorter counterparts. This reproductive discrepancy has resulted in the height difference between men and women to increasing over time, due to evolutionary pressures.