Polygenic Inheritance (Edexcel IGCSE Biology)

Spec point — 4.22 · understand that most phenotypic features are the result of polygenic inheritance rather than single genes

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)

• Polygenic characteristics often show a wider range of phenotypes, rather than just two options

• The inheritance of these polygenic characteristics is called polygenic inheritance

• Polygenic inheritance is difficult to show using simple genetic diagrams, due to the many possible combinations of alleles

• Examples of polygenic inheritance:

  • Height in humans is controlled by several genes, each contributing to how tall a person becomes. This results in a continuous range of phenotypes, from very short to very tall
  • Skin colour and weight are other examples of polygenic inheritance