What is the genotype of a normal-visioned boy whose father is colorblind?

colorblindness is usually ped onto sons by the mother. it is a recessive, linked trait that is located on the x chromosome. Since males are xy rather than xx they do not have the dominant gene to offset the recessive one. That boy inherited a Y chromosome from his father and therefore does not carry a colorblindness gene--at least not from the father anyway.