Polygenic inheritance refers to the kind of inheritance in which a single inherited phenotypic trait is produced and controlled by multiple genes. It is also known as quantitative or multi-factorial inheritance. Each gene contributing for a particular trait in polygenic inheritance has a small but addictive effect individually and exhibit incomplete dominance unlike Mendelian traits. No allele is dominant or recessive, they cannot even mask another. Because of these inheritance patterns the characteristics that are controlled by polygenic inheritance show continuous variation and can be influenced by environment. The phenotype is a blend of phenotypes inherited from parents who are alleles.
Polygenic traits have a tendency to have a bell-shaped dispensation in a population. Almost all the individuals inherit varied coalitions of dominant and submissive alleles. These individuals always comes in the middle range of the loop, which serves the average scale for a particular trait. Individuals at the ending of the curve serves those who likewise inherit every dominant alleles (on one end) or then ones who inherit all submissive alleles (on the opposite end). If we see height as an example, usually people in a population are tend to be in middle of the bend they are average height. Those on one end of the bend are tall individuals while the ones on the opposite end are definitely short individuals.
For example skin color is controlled by more than four genes and it can sometimes darken of lighten depending upon environmental factors.it is also determined by the number of dark color melanin in the skin tissues. The genes on which an individual skin color is determined contain two alleles each they can be found in chromosomes. People who doesn’t inherit any dark alleles would get very light skincolor, whereas people with dark alleles will probably have much darker skin, with different type of alleles comes varying shades of skin. Those who get even alleles of dark and light will most likely have medium skin color.
Another important trait is eye color, which is influenced by 16 divergent genes.it is decided by the number of brown color melanin that an individual have in front of the iris. Light colored eyes have no more melanin than brown or black eyes.
Other examples of polygenic inheritance include hair color, height, blood pressure, intelligence etc. in humans, milk production in cattle and nectar production in butter ups etc.