It can vary. 'Most' because most people don't "live" at high altitudes; those altitudes are quite extreme. It is difficult to put in a prospective, there is no other mountain range like Himalayas and Karakoram.

Additionally, there are many serious scientific research regarding Sherpas in this specific matter.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3515610/