Question

Certain phenotypes in human population are spread over a gradient and reflect the contribution of more than two genes. Mention the term used for the type of inheritance? Describe it with the help of an example in human population.

Answer 1

Polygenic inheritance

• If we assume skin colour is controlled by three genes A, B, C

• Dominant forms (A,B,C) are responsible for dark skin colour and recessive form (a, b, c) for light skin colour

• The genotype with all dominant alleles (AABBCC) will be darkest skin colour and with recessive alleles will be light test skin colour (aabbcc)

• The genotypes (AaBbCc) will be of intermediate skin colour i.e. with three dominant alleles and three recessive alleles