The blue-eyed father and the brown-eyed mother have all brown-eyed children.

The blue-eyed father and the brown-eyed mother have all brown-eyed children. Write down the genotypes of children and parents. What law is in effect in this case?

Since all children of this pair have a realized maternal trait (brown eyes) in their phenotype, it should be concluded that the gene that determines the development of brown eyes is dominant, as well as that the mother is homozygous for the gene for this trait.

Let’s designate the gene for brown eyes as C, then the gene for blue eyes will be c.

The blue-eyed father will be cc, since homozygosity for this gene is a prerequisite for the manifestation of this trait. Such a father produces sperm of the same type – c.

As mentioned above, the absence of cleavage based on eye color in the offspring allows us to conclude that the mother is homozygous for the gene for brown eyes. We write down its genotype as CC, and the eggs produced by it as C.

All children born to this married couple will be brown-eyed and heterozygous – Cc.

This problem demonstrates a genetic law called the uniformity law of F1 hybrids.