Question

In humans, at least one gene produces melanin skin pigment in response to UV radiation (that is, pigment production increases in response to sun exposure, leading to tanning). Thus, a human may have dark skin if they have been exposed to lots of sunlight but may have light skin if they have not been exposed to sunlight. What kind of inheritance is this an example of?

		Pleiotropy
		Polygenic inheritance
		Epistasis
		Gene-environment interaction

Answer 1

• Polygenic inheritance

Polygenes (poly= many/ multiple genes), where multiple no. of genes are involved in determining the trait. When it comes to skin colour, mostly 3 genes plays a major role in determining the colour of skin such as dark skin colour allele is dominant (D) one when compared to light skin colour allele which is recessive (d) one. When the dark allele is expressed more, the colour of the skin becomes more darker and when the D allele is expressed less, the colour of the skin becomes light.