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Polygenic Inheritance (Edexcel IGCSE Biology (Modular)): Revision Note

Exam code: 4XBI1

Lára Marie McIvor

Last updated

Edexcel Biology (Modular): Unit 2Edexcel Science (Double Award): BiologyEdexcel Biology

Polygenic Inheritance

  • Most characteristics are a result of multiple genes interacting, rather than a single gene

  • Characteristics that are controlled by more than one gene are described as being polygenic (poly = many/more than one)

  • Polygenic characteristics have phenotypes that can show a wide range of combinations of features

  • The inheritance of these polygenic characteristics is called polygenic inheritance 

  • Polygenic inheritance is difficult to show using genetic diagrams because of the wide range of combinations

  • An example of polygenic inheritance is eye colour – while it is true that brown eyes are dominant to blue eyes, it is not as simple as this as eye colour is controlled by several genes

  • This means that there are several different phenotypes beyond brown and blue; green and hazel being two examples

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Lára Marie McIvor

Author: Lára Marie McIvor

Expertise: Biology, Psychology & Sociology Subject Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.