Redheads are a product of rare genetics, and a unique gene mutation is what causes ginger whiskers to sprout from brunette’s chins. According to specialists, there are two recessive genes that combined, produce red hair and red beard. Having just one of these recessive genes is what causes red hair to sprout in unusual areas, other than the head.
"The genes that determine hair color are so-called ‘incomplete dominant hereditary traits.’ This means that there isn’t one single gene that’s dominant over the rest, but all genes influence each other,” Petra Haak-Bloem, a specialist at Erfocentrum, the Dutch national information center for genetics, told Motherboard.
The specific gene affected by the mutation is the MC1R gene, responsible for protein synthesis involved in the production of melanin, the same chemical that determines how your skin tans and the eventual colour of your hair. Thanks to this MC1R mutation, our red-bearded mates have both eumelanine and pheomelanine pigments, which means mis-matched red hair can pop up anywhere on their bodies, from eyebrows to pubic hair.
If you’ve got ginger stubble, your great-great-grandfather may be the cause. It’s more than likely your distant relatives were redheads, and the suppressed gene is finding it’s way out through your chin. "It’s entirely possible that one distant ancestor had a hair color that suddenly appears again through a certain combination of genes—and that can be quite unexpected for parents,” Haak-Bloem says.
The trait isn’t entirely rare, so don’t be afraid to embrace it. After all, the only known cure for red beard is shaving.