Question

Explain why generally only the male child suffers from colour blindness and not the female?  

Answer 1

Colourblindness is caused by recessive genes which occur on the X chromosome.

Males have only one X chromosome. If there is a recessive gene present on the X chromosome, then the male will suffer from colour blindness.

Females have two X-chromosomes. It is highly unlikely that both X chromosomes carry abnormal genes. As a result, if one gene is abnormal and recessive, the normal gene present on the other X chromosome will mask its expression. Females are unlikely to suffer from colourblindness.

The following cases explain the sex-linked inheritance of colour blindness.

Case 1

Case 2