Scientists believe they have plucked out the genetic culprit primarily responsible for graying hair.
The gene, called IRF4, has been known to play a role in determining hair color, but it is now believed to be linked to a loss of pigmentation in hair that happens as people age.
Researchers from the University College London pinpointed the gene in a study recently published in the journal Nature Communications.
They examined DNA from more than 6,500 people of mixed ancestry in Mexico, Brazil, Colombia, Chile and Peru. In their analysis, they also found genes associated with curly hair, beard thickness and unibrow.
Of course, the ratio of salt and pepper in hair and the rate at which it happens varies depending on the individual head. People go gray or even white — quickly or gradually — as hair follicles run out of the pigment that gives their hair its natural color.
But genes aren’t the only factor, scientists say. About 70 percent of gray hair is caused by environmental factors, including stress, sun exposure and smoking.
In the study, researchers wrote that they hope the gray gene discovery will help to learn how to delay or even prevent graying hair and, more importantly, to discover more about the biology of aging.