Uniformity may also lead to deformities in animals. Diversity is tied to genes , which are the basic units of heredity . A daughter resembles her parents because she inherited half of her genes from each parent. Brothers and sisters resemble each other because they have many genes in common. Identical twins look the same because all of their genes are the same.
Genes carry the information used to produce the proteins required by an organism.
Biologists recognize that the combination of an organism's genes and its environment determines how it grows and functions. Sometimes a gene's function is obvious. For example, genes determine eye color. At times a gene may be harmful and at other times useful. Its value depends on the other genes present and the environment.