In humans, dark hair color is determined by the dominant gene A, and light hair color is determined

In humans, dark hair color is determined by the dominant gene A, and light hair color is determined by the recessive gene a. A fair-haired father and a dark-haired mother had 8 children with dark hair. Determine the genotypes of the parents.

According to the introduced designations, we will write down the genotypes of the parents.

A fair-haired father will be aa, because homozygosity is a prerequisite for the phenotypic realization of a trait that is recessive.

In combination with the dominant gene, the priority, dominant phenotype determined by it is invariably realized.

Since all children of this couple have dark hair color, and from their father they all receive only the gene for light hair, it means that they inherit from their mother only the dominant gene – A. The genotype of a woman capable of producing exclusively eggs with the dominant gene A must be homozygous – AA.

Answer: father – aa, mother – AA.