Cymet suspects that going gray is "genetically outlined, but stress and lifestyle give you variation of plus or minus five to 10 years." Blonds often appear to go gray later in life because white strands easily hide in a sea of light hair when in fact those who are likely to have the darkest hair (people of African and Asian ancestry) seem to retain their color longer.In short, scientists are beginning to gather clues that stress can hasten the graying process, but there is no scientific evidence demonstrating a cause-and-effect relationship. So what happened to Marie Antoinette? There are at least three possible explanations: She may have suffered from sudden onset of the rare autoimmune disease alopecia areata, which attacks pigmented hairs, causing them to fall out, leaving the white (nonpigmented) strands behind. Or the stress of the situation could have generated a swarm of free radicals in her hair follicles, which traveled along the hair shafts, destroying pigment and creating a bleaching effect. Or maybe she just stopped wearing her wigs—revealing she had gray hair all along.