A blue-eyed man married a brown-eyed woman whose mother had blue eyes; from this marriage, a blue-eyed

A blue-eyed man married a brown-eyed woman whose mother had blue eyes; from this marriage, a blue-eyed daughter was born and a brown-eyed son to determine the geno type seven.

Let the gene for the development of blue eyes in humans be designated as m, then the gene for brown eyes will be M.

The mother of a brown-eyed woman entering into marriage had, according to the condition of this problem, blue eyes. Consequently, she had a homozygous mm genotype and produced the same type of eggs m, so she could pass on to her daughter only the gene that causes the development of blue eyes.

Therefore, the brown-eyed woman is heterozygous – Mm. She is capable of producing eggs of two types – M and m.

The blue-eyed man, like the woman’s mother, has the mm genotype homozygous for the gene for the recessive trait. It produces the same type of spermatozoa m.

The offspring of these men and women are formed by the following possible options:

children homozygous for the recessive gene with blue eyes (mm) – 50%;

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

Consequently, the daughter born by them with blue eyes has the mm genotype, like her father, and the son with brown eyes has the Mm genotype, like his mother.