A normal visioned woman, whose father is colour blind, marries a normal visioned man. What would be probability of her sons and daughters to be colour blind? Explain with the help of a pedigree chart.

Colour blindness is common hereditary condition which means it is passed down from parents. Red/green colour blindness is passed from mother to son on the 23^rd chromosome, which is known as the sex chromosome. The faulty gene for colour blindness is found only on the X chromosome.

When the father is colour blind, he can only pass an X chromosome to his daughter. Thus she acquires the gene and become the carrier of the disease.When she has a child she will give one of her X chromosome to her child. If she gives the X chromosome with a faulty gene to her son he will be colour blind, but if the son gets good chromosome then he won’t be colour blind. But there is no chance for her daughter to be colour blind; she can be a carrier if the faulty X chromosome is inherited by her from mother otherwise she is normal as the father is a normal visioned man.