Do they really?

https://www.atherosclerosis-journal.com/article/S0368-1319(6...

>A field survey of 400 Masai men and additional women and children in Tanganyika indicates little or no clinical or chemical evidence for atherosclerosis.

https://academic.oup.com/aje/article-abstract/95/1/26/167903

> The coronary arteries showed intimal thickening by atherosclerosis which equaled that of old U.S. men.

This one was brilliant. If you read the whole study, even the 18 year olds are affected. One 25 year old died of congestive failure.

> The hearts and aortae of 50 Masai men were collected at autopsy. These pastoral people are exceptionally active and fit and they consume diets of milk and meat. The intake of animal fat exceeds that of American men. Measurements of the aorta showed extensive atherosclerosis with lipid infiltration and fibrous changes but very few complicated lesions. The coronary arteries showed intimal thickening by atherosclerosis which equaled that of old U.S. men. The Masai vessels enlarge with age to more than compensate for this disease. It is speculated that the Masai are protected from their atherosclerosis by physical fitness which causes their coronary vessels to be capacious.

The same trick is used by egg studies to show that additional eggs do not increase already high cholesterol.

Doing genetics is also a huge dimensionality curse. You're fitting a high dimensional object with a curve that will most certainly fit well.