Palo Alto, California (The Adobo Chronicles) – A new study by a research team at Stanford University has identified the genetic triggers to hair color, specifically blond hair.

The new study published in Nature Genetics finds that a switch of a single letter of the genetic code is responsible for lighter hair: An A (adenine) is changed to a G (guanine) on a region of human chromosome 12. The team says that because this specific genetic change only affects the hair follicle, other cell types — especially, say, brain cells — are not affected. This means that blond hair really is “only skin deep.”

“It’s clear that this hair color change is occurring through a regulatory mechanism that operates only in the hair. This isn’t something that also affects other traits, like intelligence or personality, ” the study concluded.

The stereotype of blonds being dumb is therefore just that, a stereotype.

Except when your name is Justin Bieber — the new and improved blond Justin Bieber!