Tracey Harrington McCoy
June 03, 2014 12:45 pm

Talk about blonde ambition: after more than a decade of research, scientists have isolated the gene that determines a person’s hair color. Researchers reveal that one single tweak of DNA code determines whether a person will rock a head of blonde tresses vs. brown locks.

One small change to genetic code and brown hair becomes blonde. Get ready, we’re about to go all scientific on you: “The tiny, one-letter mutation isn’t even in the gene controlling hair growth,” the Today Show reports. “It’s miles away — in genetic terms — in what scientists used to think was “junk” DNA. It’s a genetic switch that reduces the activity of a seemingly unrelated gene.”

“It’s an example of a trait that is only skin deep,” said David Kingsley, a Howard Hughes Medical Institute investigator at Stanford University who led the study.

The study also confirmed that the specific gene isn’t responsible for anything else but hair color. It doesn’t affect intelligence (obviously), eye color, or skin color. “This particular genetic variation in humans is associated with blond hair, but it isn’t associated with eye color or other pigmentation traits,” says Kingsley. “It shows blonde hair doesn’t have anything to do with anything but blonde hair.”

Kingsley is quick to point out that there’s more than one gene responsible for blonde hair. He says people have a bunch of genes that determine hair color, and others that affect overall coloring. The specific gene they discovered is common among people living in Iceland and in Scandinavia.

So how was this ‘blonde gene’ discovered? It began with a fish. Yes, a fish. Kingsley’s research team discovered this particular “blonde gene” mutation while studying stickleback fish, a species of fish that changes their coloring depending on the water in which they’re swimming. Who knew?

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