Explanation:

Human skin colour is a complex trait that is not controlled by a single gene or allele. It is influenced by a combination of genetic and environmental factors. However, the genetic basis of skin colour has been studied extensively, and it is known that multiple genes are involved in determining skin colour.

Multiple Genes Control Skin Colour:

Research has shown that at least three separate genes are involved in controlling skin colour. These genes are located on different chromosomes and each gene has multiple alleles. This means that there are many possible combinations of alleles that can result in different skin colours.

Melanin Production:

One of the key factors in determining skin colour is the production of a pigment called melanin. Melanin is produced by cells called melanocytes, which are located in the skin. The amount and type of melanin produced by these cells are controlled by genes.

Different Alleles:

There are different alleles of the genes that control melanin production, and each allele can result in different levels of melanin production. For example, one allele may result in high levels of melanin production, while another allele may result in low levels of melanin production.

Additive Effect:

The effect of each allele is additive, meaning that the more copies of the high melanin production allele a person has, the darker their skin will be. Conversely, the more copies of the low melanin production allele a person has, the lighter their skin will be.

Environmental Factors:

In addition to genetic factors, environmental factors such as exposure to sunlight can also influence skin colour. Sunlight can stimulate melanin production, resulting in darker skin. However, excessive exposure to sunlight can also increase the risk of skin cancer.

Conclusion:

In conclusion, human skin colour is controlled by multiple genes, with each gene having multiple alleles. The combination of these alleles determines the amount and type of melanin produced by melanocytes, which in turn influences skin colour. Environmental factors such as sunlight can also influence skin colour.

Human skin color is an example of polygenic inheritance and it is control by at least 3 genes.....