skin colour of humans are polygenic
When a character is controlled by more than one gene (non-allelic) then this character is called polygenic inheritance. Polygenic trait is controlled by more than one pair of non allelic genes & shows a different types of phenotypes.
The skin colour in humans is controlled by many genes with their own alleles. These genes control the production of melanin in skin.
Suppose ABC controls the skin colour in humans and abc are the recessive homologue of these three genes.
Alleles A, B and C produce melanin while as allele a, b, c do not produce melanin. Thus, we can say that individuals with genotype
AABBCC are darkest
AaBBCC are less darker
AaBbCC are much less darker and so on.
In the same manner there is a range in the skin colour variation that indicates polygenic inheritence.
The skin colour in humans is controlled by many genes with their own alleles. These genes control the production of melanin in skin.
Suppose ABC controls the skin colour in humans and abc are the recessive homologue of these three genes.
Alleles A, B and C produce melanin while as allele a, b, c do not produce melanin. Thus, we can say that individuals with genotype
AABBCC are darkest
AaBBCC are less darker
AaBbCC are much less darker and so on.
In the same manner there is a range in the skin colour variation that indicates polygenic inheritence.