Heredity refers to the genetic heritage passed down by biological parents. It is the sum of all biological processes by which particular characteristics are transmitted from parents to their offspring. Heredity encompasses two seemingly paradoxical observations about organisms: the constancy of a species from generation to generation and the variation among individuals within a species. Constancy and variation are two sides of the same coin, as becomes clear in the study of genetics.

Heredity is responsible for the transmission of traits from one generation to the next. These traits can include physical characteristics, such as eye color, hair color, and height, as well as behavioral and personality traits. The transmission of these traits occurs through genes, which are segments of DNA that carry the instructions for making proteins.

The study of heredity is an important part of genetics, which is the branch of biology that deals with the study of genes, genetic variation, and heredity in organisms. Understanding heredity is important in fields such as medicine, agriculture, and evolutionary biology.