[Request] - Has anyone taken Genetics 270?

The phenotype is dominant. It is most likely that both the father and mother are carriers and it looks like it's sex-linked. The father will most likely have the allele on the y chromosome. In this case, all male progeny regardless of the allele inherited from the mother will carry the y chromosome and the dominant phenotype nature of the allele will cause all male progeny to be dark. For the case of a female progeny, it will definitely inherit the x chromosome from the father and it will not contain the allele. Hence, it will depend on what is inherited from the mother. Since the mother is a carrier, there will be a 50% chance of inheriting either the normal or affected allele. Hence, the chance for a female progeny to be dark is 50%.

Why add a request tag on a question?

Anyway, the gene is dominant, but the mother or/and father are/is a carrier. Read the attachment.