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What is a Polygenic Inheritance?

Polygenic inheritance refers to any trait, such as human skin color, that can be expressed in varying gradients because it is influenced by multiple genes.
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  • Written By: Mary McMahon
  • Edited By: Bronwyn Harris
  • Last Modified Date: 13 October 2014
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The term “polygenic inheritance” is used to refer to the inheritance of quantitative traits, traits which are influenced by multiple genes, not just one. In addition to involving multiple genes, polygenic inheritance also looks at the role of environment in someone's development.

Because many traits are spread out across a continuum, rather than being divided into black and white differences, polygenic inheritance helps to explain the way in which these traits are inherited and focused. A related concept is pleiotropy, an instance where one gene influences multiple traits.

Early Mendelian genetics focused on very simple genetic traits which could be explained by a single gene. For example, a flower might appear in either orange or yellow form, with no gradation between the colors. By studying plants and the ways in which they mutated, early researchers were able to learn more about the gene which determined flower color. However, by the early twentieth century, people were well aware that most traits are far too complex to be determined by a single gene, and the idea of polygenic inheritance was born.

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One easily understood example of polygenic inheritance is height. People are not just short or tall; they have a variety of heights which run along a spectrum. Furthermore, height is also influenced by environment; someone born with tall genes could become short due to malnutrition or illness, for example, while someone born with short genes could become tall through genetic therapy. Basic genetics obviously wouldn't be enough to explain the wide diversity of human heights, but polygenic inheritance shows how multiple genes in combination with a person's environment can influence someone's phenotype, or physical appearance.

Skin color is another example of polygenic inheritance, as are many congenital diseases. Because polygenic inheritance is so complex, it can be a very absorbing and frustrating field of study. Researchers may struggle to identify all of the genes which play a role in a particular phenotype, and to identify places where such genes can go wrong. However, once researchers do learn more about the circumstances which lead to the expression of particular traits, it can be a very rewarding experience.

In pleiotropy, on the other hand, one gene is responsible for multiple things. Several congenital syndromes are examples of pleiotropy, in which a flaw in one gene causes widespread problems for a person. For example, sickle cell anemia is a form of pleiotropy, caused by a distinctive mutation in one gene which leads to a host of symptoms. In addition to causing mutations, pleiotropy also occurs in perfectly normal genes, although researchers tend to use it to track and understand mutations in particular.

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Discuss this Article

anon281501
Post 25

@anon144458: Yes.

@Anon150024: No (multiple alleles).

anon150024
Post 23

Are blood types an example of Polygenic Inheritance?

anon144458
Post 22

question: is eye color for humans polygenic inheritance?

anon132723
Post 21

great page. this is very helpful. thanks to all of you.

anon84211
Post 18

Thanks a lot.

anon79125
Post 17

no no. Don't include more technical details. You have impossible-to-understand articles all over the internet to use. Leave one simple one for someone who just needs a summary.

anon78338
Post 16

thanks a lot. But it's much more informal. Include more technical details.

anon76050
Post 15

Thanks! This was very helpful for my biology project!

anon74251
Post 14

it really helped me a lot.

anon65247
Post 13

thanks! brief but concise explanation. Big help for me.

anon64031
Post 12

so would the chromosomes of a polygenic inheritance be autosomes?

anon63582
Post 10
anon62723
Post 9

this helped me very much. thank you.

anon62638
Post 8

so there are only three traits that a person has then? Like, hair, height, and eye color?

sorry I'm just trying to answer a bio question with graphs and I just needed to know if we only had three polygenic inherited traits.

anon58392
Post 7

thank you. this really helped with my science homework.

anon57465
Post 6

this did help with my bio assessment.

anon56871
Post 5

thanks for this brief and informative article. it really took a confusing subject and made it simple!

anon55423
Post 3

thank you! very helpful.

anon53484
Post 2

Very helpful!

anon48824
Post 1

fantastic page for my assignment on polygenic inheritance. thanks to all of you.

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