Polygenic Inheritance

• Monogenic Inheritance

  • involves only one gene
  • It only gives two possible traits of the offspring
  • In the case of the pea plant’s pod color
• Polygenic Inheritance/Multiple Gene Inheritance

  • In multiple gene inheritance, the trait of an individual is controlled by more than one gene
  • It is also called polygenic inheritance
  • Multiple gene inheritance results in wide variations among individuals
  • Each gene involved contributes to the trait of an individual in an additive effect
  • The location of these genes aids in variability
• Characters of living organisms are mostly controlled by multiple genes where each gene can have more than a single pair of alleles. This multiple factor inheritance greatly contributes to high variation among individuals.
• In multiple gene inheritance

  • the controlling genes can be located on the same chromosome or different chromosomes
  • If the genes are located on a single chromosome, there is a tendency that it will be inherited together
  •  if the genes are on different chromosomes, controlling similar characteristics, it can be separated during meiosis
  • The genes can be inherited independently of one another
• Independent assortment also comes into play when genes are located on non-homologous chromosomes
• Genes on non-homologous chromosomes undergo recombination in various ways. Due to this, the inheritance of traits in multiple gene patterns is highly complex leading to many possible phenotypes. An example of a trait exhibiting this pattern is skin color.
• Polygenic inheritance involves multiple alleles from both parents, which has an additive effect. These are known as additive alleles
• An individual that inherits more copies of additive alleles will express the traits by a larger degree. An example of a trait that is coded for by additive alleles is skin color, where several genes work together to express the trait. Other examples are height and hair color.
• In contrast, non-additive alleles do not follow the patterns of inheritance seen in additive alleles. Inheriting multiple alleles does not intensify the expression of the trait.
• Skin color is influenced by multiple genes
• Multiple gene traits or polygenic traits are influenced by the environment. Environmental factors can highly influence the phenotype of an individual.
• The intensity of sunlight or even the nutrients in your food can affect gene expression in individuals. In most organisms, multiple genes control the size, shape, and color of an individual. Other multiple gene traits are behavior, intelligence, and height.
• Epigenetics 


  involves the study of factors like behavior and the environment on the expression of genes.