No, the "Blonde Gene" Does Not Make You Dumb

The exact genetic change that creates blonde hair has been identified, providing more insight into how the human genome works and proving once-and-for-all that being blond has nothing to do with intelligence.

A study published in the peer-reviewed journal Nature Genetics details how researchers have finally identified the exact genetic mutation that can make a person blonde, in-turn identifying the influential molecule that determines the hair color of every human being.

"We've been trying to track down the genetic and molecular basis of naturally occurring traits - such as hair and skin pigmentation - in fish and humans to get insight into the general principles by which traits evolve," study author David Kingsley said in a statement. "Now we find that one of the most crucial signaling molecules in mammalian development also affects hair color."

According to the study, a protein called KITLG heavily influences how hair color is expressed. The protein, which is instrumental in many stem cell processes, aids in the formation of blood, egg, and sperm cells in addition to hair pigmentation. However, the "blonde gene" mutation appears to affect this protein in hair follicles alone, without altering how KITLG is expressed in the rest of the body.

Researchers determined this after analyzing the DNA of a great number of blonde people in Iceland, identifying one single letter-change mutation that appeared to be associated with blondeness. They then extensively observed what this mutation did to human cells in the lab.

This analysis showed that the mutation affected hair follicles alone, and did not influence any other developmental processes in the human body - effectively proving that being blonde has nothing to do with intelligence, in spite of the age old stigma.

Animal testing helped prove this point, given that normally brown-colored mice were born with lighter coats when genetically altered to express the single mutation.

"It's clear that this hair color change is occurring through a regulatory mechanism that operates only in the hair," Kingsley said. "This isn't something that also affects other traits, like intelligence or personality. The change that causes blond hair is, literally, only skin deep."

The study was published in Nature Genetics on June 1.