A brown-eyed boy, whose father is blue-eyed, married a blue-eyed girl.

A brown-eyed boy, whose father is blue-eyed, married a blue-eyed girl. What is the likelihood of a rebunk with blue eyes being born? brown-eyed is the dominant feature.

Let’s designate the gene for the dominant trait (brown-eyed) as K, then the gene for the recessive trait (blue-eyed) will be k.

The blue-eyed father of the young man had a homozygous kk genotype, because only under the condition of homozygosity a recessive trait can be realized in the phenotype. He produced sperm of the same type k and could only pass on the recessive gene for blue eyes to his son. Consequently, the brown-eyed young man is heterozygous – Kk. It is capable of producing two types of sperm – K and k.

The blue-eyed girl, like the boy’s father, is homozygous – kk. It is capable of producing only eggs of the same type k.

The offspring from this marriage will be represented by options:

homozygous children with blue eyes (kk) – 50%;

heterozygous children with brown eyes (Kk) – 50%.

Answer: 50%.