How are multiple genes involved in the inheritance of skin colour?

Skin colour is a polygenic trait, meaning it is determined by multiple genes that interact in complex ways.

Skin colour is a classic example of a polygenic trait, which is a characteristic that's influenced by more than one gene. These genes are located on different chromosomes and each contributes to the final phenotype, in this case, the colour of the skin. The genes involved in determining skin colour produce varying amounts and types of melanin, the pigment responsible for skin, hair, and eye colour.

The two main types of melanin are eumelanin, which is brown or black, and pheomelanin, which is yellow or red. The amount and type of melanin produced by your body ultimately determine your skin colour. For instance, individuals with darker skin have more eumelanin and less pheomelanin, while those with lighter skin have less eumelanin and more pheomelanin.

The genes that control the production of melanin are not dominant or recessive, but additive. This means that the more 'dark skin' alleles a person has, the darker their skin will be. Conversely, the more 'light skin' alleles a person has, the lighter their skin will be. This is why skin colour can vary so widely among individuals and populations.

Furthermore, the expression of these genes can be influenced by environmental factors such as sunlight exposure. For example, exposure to sunlight can stimulate the production of melanin, leading to a darker skin colour. This is a protective mechanism to prevent damage to the skin from harmful UV radiation.

In conclusion, the inheritance of skin colour is a complex process that involves multiple genes and environmental factors. It's a fascinating example of how our genes interact with the environment to produce the diverse range of human skin colours we see today.