As a geneticist with a focus on human genetics, I can explain the concept of genetic dominance in the context of hair color. Hair color is determined by multiple genes, with the most significant being the melanocortin 1 receptor (MC1R) gene. However, the question of whether brown or red hair is more dominant is not straightforward because the inheritance of hair color is polygenic, meaning it involves multiple genes.
The MC1R gene, for instance, has several variants that can lead to different hair colors. The eumelanin (black/brown pigment) produced by this gene is more dominant than pheomelanin (yellow/red pigment). However, the presence of red hair is due to a specific variant of the MC1R gene that is recessive. This means that an individual must inherit two copies of the recessive variant (one from each parent) to express red hair.
To summarize, while the production of brown pigment is genetically dominant over red, the specific gene variant that results in red hair is recessive. This means that for a child to have red hair, both parents must carry the gene variant for red hair, even if they do not express it themselves.
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