A colour-blind child is born to a normal couple. Work out a cross to show how it is possible. Mention the sex of this child.
Colour blindness is a sex-linked disease. The gene for this disorder is present on the X chromosome. Hence, it is carried by normal females not expressing the disease.
If a colour-blind child is born to a normal couple, then the mother would be the carrier of the disease. The child would be male.
The following cross shows the inheritance of the disorder: