Question

1. A woman with white skin has intermediate parents. If this woman marries a man with light skin, what is the darkest skin color possible for their children? The lightest?

2. A woman is color blind. What are the chances that her sons will be color-blind? If she married a man with normal vision, what are the chances that her daughters will be color blind?

Answer 1

1. The darkest color is also possible and the lightest color is also possible. The children can also get intermediate skin tone.

2. Color blindness is a genetic disorder, “X-linked recessive” disorder. X-linked because the gene that gets affected is carried on the X chromosome and recessive because a different version of the gene can dominate it. Thus more males are affected than females by color blindness. The gene that gets expressed masks the effect of the other gene.

So, if a woman is color blind and is married to a man with normal vision, there is 100% chance that the sons will be color blind. The chances of daughters being color blind is 0% but they'll always be carriers. (Check the pedigree chart below)

obliCNormel father) (mother) Affected so n (a lour blind) Carrier γγ1er daughters