"Expect extreme genetic outliers in any large population A study of 585 people running the exact same 12-week bicep training program showed that while most subjects grew about 20%, a small number gained zero muscle and a few gained 55% — on identical programming. The takeaway: genetic variation in response to training is enormous, so "someone is the most muscular without taking steroids" just as surely as someone is the world's tallest or oldest. Practically, this means you should not assume an unusually impressive natural physique is fake, nor should you use outlier results as your personal benchmark. Source: Jeff Nippard, YouTube, How Big Can You Get Naturally? (Science-Based)"