Colorblind males will have a normal Y chromosome and an X chromosome with the recessive trait, expressed as XoY, with "o" representing the color blindness trait. Colorblind females will have two affected X chromosomes (XoXo). Together, a colorblind father and a colorblind mother will produce colorblind sons and daughters. Let the genotype for a male child with color blindness be XoY and for a female child, the genotype would have to be XoXo.
