How Genetic Differs From Heredity

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In the simplest terms, the adjective “genetic” means anything that pertains to a person’s gene sequence that exists within every living cell. Genes are the basic component of heredity in humans and other living organisms.

Twin babies looking at each other face to face
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Genes are made up of DNA, or deoxyribonucleic acid. According to the National Human Genome Research Project identify and map the genetic sequence of humans — we have an estimated 20,000.

Remarkably, approximately 99% of genes are the same in all people, with the remaining tiny proportion responsible for the differences we see in height, skin color, weight, and other physical traits.

The Genetic Theory of Aging

The genetic theory of aging suggests that longevity is also determined by our genes, and some research — such as studies involving identical twins — supports this hypothesis. Other studies have estimated that a person’s lifespan is only about 25% attributable to their heredity and much more likely to be influenced by lifestyle factors like diet and exercise, and harmful habits like smoking or alcohol abuse.

Further, an emerging field of health science research called epigenetics aims to determine why some genes are "switched on" in the body, and others are not, causing certain physical characteristics or vulnerability to disease, for example.

This area of study looks at influencing factors such as maternal stress or environmental exposure, and can at least partially explain why identical twins have physical differences despite possessing the same genetic makeup.​

Genetic vs. Hereditary

While the term genetic is often used interchangeably with the adjective hereditary, these words don't necessarily mean the same thing. For example, cancer is a genetic disease in that it involves the genes within a cell (causing that cell to divide uncontrollably), but cancer itself may be caused by sun or tobacco exposure and is not necessarily inherited from your parents.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. MedlinePlus. What is a gene?

  2. American Society of Human Genetics. Building Blocks of the Genetic Code.

  3. Johansson B, Thorvaldsson V. What matters and what matters most for survival after age 80? A multidisciplinary exploration based on twin data. Front Psychol. 2021;12:723027. doi: 10.3389/fpsyg.2021.723027

  4. Passarino G, De Rango F, Montesanto A. Human longevity: Genetics or Lifestyle? It takes two to tango. Immunity & Ageing. 2016;13(1):12. doi: 10.1186%2Fs12979-016-0066-z

  5. Hoffmann A, Zimmermann CA, Spengler D. Molecular epigenetic switches in neurodevelopment in health and disease. Front Behav Neurosci. 2015;9. doi: 10.3389/fnbeh.2015.00120

  6. American Cancer Society. Genetics and Cancer.

Additional Reading

By Sharon Basaraba
Sharon Basaraba is an award-winning reporter and senior scientific communications advisor for Alberta Health Services in Alberta, Canada.