MedlinePlus: Is hair color determined by genetics? The MC1R gene is also responsible for freckles in many redheads. The combination of the two genes is what gives the child their red hair. If parent A has red hair and parent B does not (but they carry the gene) there is a 50% chance their child will have red hair. All of that means that even if two people have the exact same combination of multiple genes they might still have different color hair. When a baby receives an allele for red hair, it will blend with its accompanying allele. //-->