Red green colourblindness is a sex linked inheritance character. The genes b for colourblindness is recessive to the genes B for normal vision the genes b is carried only on the x chromosome

Dear Student, In colourblindness, the gene for normal vision is dominant. The normal gene and its recessive allele are carried by X-chromosome. In female colour blindness appears only when both the sex chromosome carry the recessive gene. The females have normal vision but function as carrier if a single recessive gene for colour blindness is present . Hoewever in males the defect appears in the presence of a single recessive genes because Y-chromosome of male does not carry any gene for colour vision. Thank You!