The allele for color blindness (c) is on the X chromosome. C is the wildtype allele. How is the color blindness phenotype effected by the sex of the offspring, if the maternal genome carries 2 copies of the color blindness allele (XcXc) ? The paternal genotype is XCY. only XY male offspring can express the color blindness phenotype only XX female offspring can express the color blindness phenotype all offspring express the phenotype, regardless of sex neither sex offspring express the phenotype.