You have two robots in front of you. We’ll call them, oh, I don’t know, Android 17 and Android 18. They are identical. Built to replicate human function as best as mechanically possible.
Your test them for power output, movement capabilities, and intelligence. And then you drop Android 17 into a desert. You drop Android 18 into a rain forest.
You Leave Android 17 and Android 18 alone for one year, then you rescue them. You retest them for power output, movement capabilities, and intelligence.
Nothing changes. Because they are robots. They are mechanical. Static. They have what they were built with. (Unless they break.)
Now think of you.
Think of who you are at this exact moment in time. Clone this version of you into identical humans, V1 and V2. (You are V0.)
Let V0, you, live your normal life. Drop V1 into the desert, just like you did Android 17. Drop V2 into the rain forest, just like you did Android 18.
Would there be an eventual difference between V0, V1, and V2? If humans were slave to genetics, there’d be no difference between the V’s. Ever. They’d be just like the Androids.
But you're different. You're human. Humans are organic creatures that communicate with the environment.
Although V0, V1, and V2 start as the same person, they wouldn’t end as the same person. The environment would change each V both physically and mentally.
V1 would have all sorts of skills and knowledge about the rain forest that would be foreign to both V2 and V0. He knows the growl of a jaguar. He knows when to run away from a certain rustling in the bushes. He knows how to climb trees, and his upper body muscle shows it. His body handles humidity better.
V2 would have all sorts of skills and knowledge about the desert, like the sound of a rattlesnake tail. His feet are built to handle the the sand. He has skills that the desert demanded him to build. Skills that neither V1 or V0 have.
See what's happening?
It's almost like Mega Man beating a Robot Master and gaining its ability. Kill Ring Man, become Ring Man. Kill Drill Man, become Drill Man.
V1 kills the rain forest and becomes Rain Forest Man. V2 kills the desert and becomes Desert Man.
You adapt to the world around you. You sit in the sun, you get a tan. You lift bricks for a living, you build calluses. You lift weights for a living, you build muscles.
These are all things that happen because of the environment.