Red hair is caused by a mutation in the melanocortin 1 receptor (MC1R) gene. This gene is responsible for regulating the production of melanin, which is the pigment that gives skin, hair, and eyes their color. The MC1R gene mutation results in decreased melanin production, which can lead to red hair, light skin, and freckles.
Both Asian and Scottish people can carry the MC1R gene mutation. If both parents carry the mutation, their child has a 25% chance of being born with red hair. If only one parent carries the mutation, their child has a 50% chance of being born with red hair.
