We discuss that too. Some people have a genetic disposition to be endurance athletes, some don’t. Look at the Kenyan marathon runners. But having the genes doesn’t guarantee anything either. It takes acquired skill. Even something as seemingly simple as running 26.1 miles (seemingly simple in the sense of strategy, not physically) takes significant acquired skill to be able to maximize one’s potential. Here’s another one we discuss (in the older grades) - basketball. To be a truly elite player most often means height. Only one way to be 6’5” inches tall - genes. But how much Michael Jordan’s hand-eye coordination, kinesthetic awareness, strength, endurance, and all around basketball smarts are genetic vs acquired are a debate. I’m quite sure not everyone from that famous tribe in Kenya is a natural born marathon runner, nor has the genetic potential to be. There’s a lot to be said for the climate, altitude, and overall social support. That conversation goes over 4th graders’ heads. I’ve tried. 7th-9th graders, not so much.