A person might have a genetic predisposition to be tall, yet be short because of poor childhood diet. A plant might inherit a tendency to produce bright red blooms, but be unable to flower because of lack of nutrients. The interactions between a living thing and its environment affect how it will turn out. Domineering Genes With some exceptions, every organism has two of each kind of gene. An offspring gets one of each type from each parent.
Genes are usually either dominant or recessive.
A dominant gene is expressed in the offspring no matter what gene the other parent contributes. A recessive gene is expressed in the offspring only if both parents contribute recessive genes. For example, the gene for blue eyes is recessive. If you have blue eyes, both of your parents contributed a recessive blue gene. Mutations Rule Over the billions of years the earth has been around, plants, animals, and other living things have evolved through the changing of genes.