Question :Colour blindness is a recessive trait. A couple with normal vision has two sons - one colourblind and one with normal vision. If the couple has two daughters, what proportion of them will have normal vision?

Question :Colour blindness is a recessive trait. A couple with normal

1.	Question :Colour blindness is a recessive trait. A couple with normal vision has two sons - one colourblind and one with normal vision. If the couple has two daughters, what proportion of them will have normal vision?
Answer» Solution : As the couple is with NORMAL vision, the mother is CARRIER for the GENE. Therefore, both their daughters will have normal vision but with a possibility of 50% being carrier for colour blindness. It is clear from the GIVEN CROSS: