Dominant genes tend to overpower recessive genes. If brown hair is dominant(M) and blonde hair is recessive(m) then to have blonde hair you need m,m, brown hair would be M,M or M,m.
A dorminant gene is that which expresses itself phenotipically in a heterozygous state. A recessive gene is that whose presence is masked phenotipically due to the presence of another gene in a...