IMHO, ORAC made a wise comment above under post #58.
In critical situations, with extreme motivation and tonns of perspirationthose who may not be genetically ideal may be the best of the best.
IIRC, the average age of the British pilots ("The Few") who defended the country against "Goering aces" in 1940 was about 20. And I assume there was no thorough and timely psycho-medical selection at that time. But they won.
Even in sport, where genetics really matters, there are many examples of that kind. E.g., there is African dominance in medium and long-distance running now. Looks understandable taking into account the anthropometry of Ethiopian and Kenyan guys (thin like sticks, etc). But interesting that only 3 or 4 outperformed British Seb Coe during last 35+ years since he set his fantastic record on 800 m back in early 80's. Or Russian Vladimir Kutz in 50's - he looked more like a boxer or power lifter, but thanks to outstanding training finally became a world and Olympic champ.