heredity

Heredity is the reason children resemble their parents. It is the natural process by which biological information is handed down the generations, so that a trait present in a mother or father can reappear, in whole or in part, in a son or daughter.

The physical carrier of heredity is DNA. When organisms reproduce, they pass copies of their genes to their offspring through reproductive cells. The offspring receive a mixture of these instructions and, by following them during development, grow into bodies that echo their parents while remaining unique individuals.

Heredity is what makes biology continuous across time: a feature can persist for thousands of generations because each generation reliably copies and transmits the underlying genes. At the same time, the reshuffling of genes during reproduction, together with occasional mutations, keeps each new generation slightly varied.

It helps to separate heredity from environment. Many resemblances within a family are genuinely inherited, but families also share homes, diets, languages, and habits. Telling apart what is transmitted through genes and what is merely learned or shared is one of the central, and difficult, tasks of genetics.