Excuse Found for Blondes

From Dieneke's: A molecular basis for classic blond hair

A molecular basis for classic blond hair color in Europeans

Catherine A Guenther et al.

Hair color differences are among the most obvious examples of phenotypic variation in humans. Although genome-wide association studies (GWAS) have implicated multiple loci in human pigment variation, the causative base-pair changes are still largely unknown1. Here we dissect a regulatory region of the KITLG gene (encoding KIT ligand) that is significantly associated with common blond hair color in northern Europeans2. Functional tests demonstrate that the region contains a regulatory enhancer that drives expression in developing hair follicles. This enhancer contains a common SNP (rs12821256) that alters a binding site for the lymphoid enhancer-binding factor 1 (LEF1) transcription factor, reducing LEF1 responsiveness and enhancer activity in cultured human keratinocytes. Mice carrying ancestral or derived variants of the human KITLG enhancer exhibit significant differences in hair pigmentation, confirming that altered regulation of an essential growth factor contributes to the classic blond hair phenotype found in northern Europeans.

The original article is illustrated with this:

 Where I might have chosen:

But then, there may be some bleach involved.  Additional examples of the mutation below if you need more. . .

Linked at Pirate's Cove in the weekly "Sorta Blogless Sunday Pinup." And a belated acknowledgement of the Wombat-socho's giant Rule 5 manifesto: "Rule 5 Sunday: Floating."