Red hair
A hair color caused by a high proportion of the red pigment pheomelanin, usually expressed when a recessive MC1R gene variant is inherited from both parents. At about 1-2% of the world's population, it is the rarest hair color.
Natural redheads may need more anaesthetic. A 2004 study found people with the MC1R gene variant behind red hair needed up to 20% more, as the variant shifts hormones governing pain response. But other studies disagree, so it's too soon to generalise.
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