Terrain
I like to think of our body as the agency or consciousness that has been evolving for tens of thousands of years before my consciousness was ever aware of its existence. That my body, or any of our body's are temporary manifestations of the foundational, colonial pool of genetic life we call homo sapien.
Our genetics and our immediate environment direct our biological differences regarding visible characteristics, physiology, disease susceptibility, mental abilities, body size and life span. Though individual body's vary in many ways, two humans no matter how different they appear are more than 99% alike.
The greatest degree of genetic variation exists between males and females.