The gene for color blindness is a recessive allele located on the x chromosome. If a color blind man and color blind woman have one son and three daughters how many will be color blind?

Women can not be colorblind, only men. For questions like these a punnett square is useful. Men can not carry the colorblind trait, but women can. I know this is kind of confusing.

When a carrier ( a woman with the color blind trait) has children with a man ( color blind or not) her kids will have 50% chance of having that trait. If its a girl, she will be the carrier. If its a boy, he will have the colorblind trait.


Theoreticaly, 1 of the daughters will be the carrier, and the son will have a 50% chance of being colorblind.

Women can be colorblind, its just rare. About every 6400 women one is colour blind and with men, every 80 men 1 is colour blind.