A brown-eyed woman married a brown-eyed man, both of whose parents are also brown-eyed.

A brown-eyed woman married a brown-eyed man, both of whose parents are also brown-eyed. From this marriage, one blue-eyed child was born. Determine the genotypes of all family members based on the assumption of monogenic control of eye color.

Answer: Mom – Aa, father – Aa, child – aa.
Solution: brown-eyed parents can be either homozygous (AA) for a trait, or heterozygous (Aa). In the first case, all children will be brown-eyed, which does not suit us according to the terms of the assignment. If we consider the second option, then the birth of a brown-eyed child will be 75% and 25% of a blue-eyed one.