Question

Red-green color blindness is an X-linked recessive trait. Betty has normal color vision, but her mother is color blind. Bill is color blind. If Bill and Betty have a child together, what is the probability that the child will be color blind?

Answer 1

The probability that Bill and Betty's child will be color blind is 50% for sons and less than 50% for daughters since red-green color blindness is an X-linked recessive trait and Betty carries one normal allele.

Step-by-step explanation:

The inheritance of X-linked recessive traits like red-green color blindness. Betty has normal color vision, but since her mother is color blind and it's an X-linked recessive trait, this means Betty is a carrier of one copy of the colorblind allele. Bill, being affected, has one X chromosome with the colorblind gene.

If Bill (XcY) and Betty (XCXc) have a child:

Their daughters (XCXc or XcXc) have a 50% chance of being carriers like their mother, because they will inherit one X chromosome from each parent. However, they will only be color blind if they inherit the colorblind allele from both parents, which is unlikely since Betty has one normal allele.

Their sons (XCY or XcY) have a 50% chance of being color blind since they inherit the X chromosome from their mother and Y chromosome from their father. If they inherit their mother's carrier X chromosome (Xc), they will be color blind.

The probability that Bill and Betty's child will be color blind is 50% for any sons and less than 50% for daughters, as daughters can only be color blind if they inherit the recessive allele from both parents.