Genotype is the genetic composition. Phenotype is visible expression of genes. A person with heterozygous genes will show the dominant gene, the phenotype. That person may still pass along recessive genes to their offspring. This is why redheads and blonds can pop up in an otherwise brunette family. Note that recessive phenotypes require both genes involved to be recessive. So while a brunette might carry genes for blond or red hair, people who are very blond won't pass along brunette genes. To make matters more interesting, hair color and a lot of other things have multiple alleles. That is to say that more than one gene is involved. Another factor is gene activation. Some genes are dormant and don't make the proteins which cause whatever they do. These genes can become active and start making impacts on their body. Some cancer patients have had their gray hair return to its original color, for example.