A man whose father was colourblind marries a woman, who has a colourblind mother and normal father. What percentage of male children of this couple will be colourblind?

(1) 25%

(2) 0%

(3) 50%

(4) 75%

(3) As colourblindness is a recessive genetic disorder, the gene responsible for it is present on 'X-chromosome'. The man whose father was colourblind is normal (XY). But the woman whom he marries can be a carrier to this disease, as her mother was colour blind XcXc with a normal father (XY). Thus, in this case, the percentage of male child to be colourblind is 50%.

Difficulty Level:

  • 27%
  • 25%
  • 47%
  • 3%