Hair appearance has long been linked to genetic factors because of the apparent differences in hair on different continents. Straight hair is rare in sub-Saharan Africa, while variable hair color is less common in East Asia. But the source of gray hairs has always been disputed: genetics or stress?

It study shows the first definite evidence that gray hairs have some ties to genetics.

This particular study, called, “A Genome-wide Association scan in Admixed Latin Americans Identifies Loci Influencing Facial and Scalp Hair Features,” was conducted by Dr. Kaustubh Adhikari and his team at the University College London’s cell and developmental biology department. They analyzed 6,357 people with varied ancestry from Latin America to identify genes associated with hair color, graying, density, and shape (curly/straight). The volunteers were 55% women and included people of a variety of backgrounds, with 48% being mixed European, 46% Native American, and 6% African. The team compared individual features to whole genome results to identify which genes influenced appearance.

They found that the gene matching gray hair is IRF4 which also plays a role in hair, skin, and eye color as it regulates the production and storage of melanin, a pigment. Gray hair is caused by an absent of melanin. Further understanding of IRF4 and the production of melanin could lead to the development of methods to block or delay the gray. But, they did find that IRF4 seems to only account for 30% of gray for, the rest seems to be influenced by environmental factors.

Other discoveries include gene PRSS53 which influences hair curliness, EDAR, which influences beard thickness and hair shape, FOXL2, which influences eyebrow thickness, and PAX3 which contributes to the monobrow.

These findings could lead to more than just cosmetic purposes. From this, scientists can continue to develop forensic technologies that can establish a visual profile of a criminal or victim from an individual’s DNA. Prototypes have already been developed for people of European decent, so these new findings will flesh out reconstructions of Latin Americans and East Asians. This will also help scientists to better understand the science of aging.