Genes

Parents and children do not always look exactly alike, because parents can have the gene for a certain trait or characteristic in their cells in the chromosomes, but it may not show itself. This is a hidden gene. The hidden gene is called recessive. A gene that shows itself is called dominant.

Traits are controlled by the genes of both the mother and father. An organism with two like genes for a trait will be homozygous for that trait. However, an organism with two unlike genes for a trait is called heterozygous, or mixed, for that trait. A dominant gene always shows itself and a recessive gene is hidden when the dominant gene is present.