In a family where both parents had normal vision and had one dark and the other blond hair

In a family where both parents had normal vision and had one dark and the other blond hair, a child with blond hair was born. What is the likelihood of myopic children with dark hair appearing in a family? It is known that dark hair dominates light hair, and myopia is a recessive sign.

A – dark hair;

a – blonde hair;

B – normal vision;

b – myopia.

According to the conditions of the problem, it is known that parents with dark and light hair gave birth to a child with light hair. Therefore, for such a child to be born, it is necessary that one of the parents be a carrier of the gene with blond hair.

R: AaBb * aaBb

F1: AaBB – dark hair and normal vision, 2AaBb – dark hair and normal vision, Aabb – dark hair and myopia, aaBB – blonde hair and normal vision, 2aaBb – blonde hair and normal vision, aabb – blonde hair and myopia.

Therefore, the probability of having myopic children with dark hair is 1/8 = 12.5%.