Researchers at the University of Edinburgh have pinpointed eight genes associated with red hair, unraveling long-standing mysteries about how these striking traits are inherited. This landmark analysis—the largest genetic study of hair color to date—also illuminates the genetics of blondes and brunettes.
Traditionally, red hair has been attributed primarily to variants in the MC1R gene, requiring two copies—one from each parent—for the trait to fully express. Yet, not everyone with these variants develops red hair, hinting at other genetic influences that remained elusive until now.
By analyzing DNA from nearly 350,000 individuals of European descent, where hair color variation is most pronounced, the team compared redheads to those with brown or black hair. They identified eight novel genetic variants linked to red hair. Further investigation revealed that some of these genes regulate the activation of MC1R.
Beyond red hair, the study highlighted nearly 200 genetic differences tied to blonde and brunette shades, forming a spectrum from black through brown to blonde, driven by cumulative variants.
Surprisingly, many of these variants influence hair texture—such as curliness—and growth patterns, rather than pigmentation alone.
