You've seen them around, no doubt. On the street, in your personal life, or in the movies. Maybe even when you look the mirror. We're talking about men with dark hair but an inexplicably red beard. You may have wondered what, exactly, was up with that.
Well, wonder no more. Because science is here to save the day. Talking with Motherboard, Petra Haak-Bloem of Erfocentrum, a Dutch center specializing in genetics and hereditary traits, explained: "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."
Basically, it's a bit of a crap shoot. Genes get passed down from your parents, grandparents, and earlier ancestors. Combinations of those genes can present differently for different people, and can also lead to the same person having different-colored hair on different parts of his body. Hence the split in hair and beard color.
So why red? Basically, there's a gene called MC1R that, when it's mutated, is responsible for red hair. If it gets passed down from both parents, you get the full-blown red hair/fair skin combo. But when you've only got one mutated MC1R gene, red hair can appear in other places. Like your beard. (Even if your hair is brown.)
So, that's why it happens.
The exact mechanism for how it all goes down, though, isn't known. (It's not exactly a research priority, since it's not linked to any disorders.) Some aspects have been solved, but still the mystery of the chinger persists.
