What are the genotypes of parents and children if a fair-haired mother and a dark-haired father

What are the genotypes of parents and children if a fair-haired mother and a dark-haired father have 5 children, all dark-haired?

Since all children demonstrate the father’s phenotype, it should be concluded that the gene that causes the development of dark hair in humans is dominant, as well as the father’s homozygosity for this gene. Let’s designate the gene for dark hair as T, then the gene for light hair would be designated as t.

The blonde mother has a homozygous genotype tt, she produces the same type of eggs t and can only transmit the gene for blonde hair to her children.

The dark-haired homozygous father is TT. It produces the same type of sperm T and is only able to pass on the gene for dark hair to children.

All children in this family will be genotypically and phenotypically uniform and are represented by dark-haired Tt heterozygotes.

Answer: the mother is homozygote for the recessive gene for blond hair (tt), the father is homozygote for the gene for dominant dark hair (TT), the children are heterozygotes with dark hair (Tt).