Polygenic Inheritance

A Detailed Analysis of Polygenic Inheritance

Inheritance is the property by which an offspring draws specific characteristics from its parents. Features such as height, skin pigmentation, eye colour, hair colour, etc. are some of the polygenic inheritance examples. These are the ones which we inherit from our parents though various alleles in the genes.

Polygenic inheritance is termed as such since multiple combinations of genetic features can be inherited from parents. In simple words, there is no exact height for tall or short, which indicates there are several combinations.

For a more in-depth understanding, go through the following discussion to prepare well for your NEET exam.


What is Polygenic Inheritance?

As explained above, polygenic inheritance is found in both animals and human beings. You should note that these characteristics are not so prevalent in plants as their genetic structure is different from other living organisms.

It has been found that over 400 different genes are responsible for a single feature, say height. You might have seen around you, and people are of different heights and complexions. No two person is precisely the same. Even twins are likely to have minute differences in them.

These features are termed as traits, and as they are based on multiple genes, they are called polygenic traits. So, an attribute is inherited, but several genes control it, and hence you see the variation in people.


Traits of Polygenic Inheritance

Look at the Table Below. It shows how different Genes control a single Trait for a Human Being. 


AB

Ab

aB

ab

AB

AABB (DARK RED)

AABb (DARK)

AaBB (Dark)

AaBb (Medium)

Ab

AABb (Dark)

AAbb (Medium)

AaBb (Medium)

Aabb (Light)

aB

AaBB (Dark)

AaBb (Medium)

aaBB (Medium)

aaBb (Light)

ab

AaBb (Medium)

Aabb (Light)

aaBb (Light)

aabb (WHITE)

Make sure you are aware of the representations of genes with the help of alphabets. Also, you should be able to tally the alphabets combinations with the character they are trying to portray. 

You will see, with each combination, the colour characteristic is also mentioned for a clear understanding. Alongside that, it should be kept in mind that these are mere sign conventions. They were designed to understand the combinations that take place genetically without our knowledge.

All of this goes on to explain the fundamental polygenic inheritance definition. However, let us dig deeper into the concepts, as discussed in the upcoming section.


Role of Environment on Polygenic Inheritance

One cannot deny the role of nature in shaping the characteristics of an individual. It is because people acquire these features over time as they live on and indulge with other people too. Nevertheless, internal or inherent features are also affected by the environment. 

As already discussed, inherited traits are a continuous type and not specific phenotypes. Here, multiple genes control one characteristic, and such features are regarded as quantitative characters. Various genotypes thus control the overall phenotype of that particular trait. 

Under various environmental conditions, these genotypes switch on or off their evidence. For example, eye colour or hair colour or hair texture, etc. These are some of the polygenic inheritance examples that you can decode with the help of codes, as shown in the picture. 

Refer to it for a comprehensive understanding from the grassroots of the topic. Also, remember how to make the combinations for each gene determining a particular character.

Another exciting aspect where you can find the impact of the environment of genes is in the case of twins. If both the individuals are brought up in different backgrounds, both are likely to act and have different characteristics overall.

Other features like schizophrenia, intelligence, depression, etc. also affect differently for different people. Thus, it is evident that the environment has an effect on polygenic traits. Even though minute and visible only under certain specific circumstances, the results make up the characteristics of an individual. 


Identification of Polygenic Inheritance

The inheritance of several polygenic characteristics is evident through their outlook. For instance, a person is likely to be taller if the genes carrying ‘tall’ feature are dominant. 

Contrarily, when there is the dominance of the genes that carry ‘short’ feature, the individual is likely to be shorter in height. Likewise, even for other characteristics or traits, you can identify if it comes under the continuous spectrum of characters or is in the extremes.

It would be helpful if you could look into various sample tests both on human features and on plant seeds features. It will assist you in comprehending the information effectively. Further, your answers in the exam will be more accurate and to the point.

FAQs (Frequently Asked Questions)

1. What do you mean by Polygenic Inheritance?

Ans. Polygenic inheritance refers to the genes controlling a phenotype. Herein, various genotypes are responsible for a trait such an eye colour, height, etc. in human beings or even plants.

2. What are some examples of Polygenic Inheritance?

Ans. Some examples of polygenic inheritance are eye colour, weight, hair colour, intelligence, depression, schizophrenia, skin pigmentation, body shape, height, etc.

3. How can you identify Polygenic Inheritance?

Ans. The identification of polygenic inheritance is possible with their outlook. You can identify if a person in absurdly taller or shorter in height when the dominant gene has controlled the phenotype.