Andrew Huberman· PhD
Monozgous, identical twins mean they have the exact same DNA. So an egg was fertilized, split, and then two humans grew out of that with the exact same DNA. And so now we can start answering the question, well, yeah, OK. What about, maybe, these cross-country skiers? Maybe they were just genetic freaks. Maybe it didn't matter. It's like some people have-- well, genetics are always a component to it, but how much? Well, now we have a scenario lining up where it's like, wait a minute. You have monozygous twins. So we have a replica of a human being, exact same DNA. The only differences that we would see in their physiology now would be due to lifestyle circumstances.