Question

What is polygenic inheritance?

Answer 1

Hint: Inheritance is the mechanism by which genetic information is transferred from parent to child. That is why members of the same family seem to have similar characteristics.

Complete Answer:
- The word "phenotype" refers to the measurable physical properties of the organism, including the presence, growth and actions of the organism. The phenotype of an organism is determined by its genotype, which is the set of genes the organism bears, as well as by environmental effects on these genes

- Polygenic inheritance, also known as quantitative inheritance, refers to a single hereditary phenotypic trait regulated by two or more separate genes.

- In a system that varies from Mendelian genetics, where monogenic traits are determined by different alleles of a single gene, polygenic traits which show a variety of possible phenotypes, determined by a number of different genes and the interactions between them.

- Characteristics that are determined by polygenic inheritance are not merely an outcome of dominance and recessivity, and do not show total dominance as in Mendelian genetics, where one allele dominates or hides another. Instead, polygenic genes display incomplete dominance, such that the phenotype shown in the offspring is a combination of phenotypes shown in the parents.

- Each gene that leads to a polygenic trait has an equal impact and each allele has an additive effect on the outcome of the phenotype.

- Owing to inheritance patterns, physical traits that are regulated by polygenic ancestry, such as hair colour, height and skin tone, as well as non-visible traits such as blood pressure, intellect, autism and durability, occur on a continuous curve, with several variations in quantifiable increments.

Note: The likelihood that the offspring will inherit a certain trait from their parents can be measured by using a punnett square, but in fact there can be a large number of different genes regulating a single phenotype trait, making it difficult to show. Luckily, the distribution of phenotypes determined by polygenic inheritance typically falls into a typical distribution of probabilities, with most offspring exhibiting an intermediate phenotype of both parents.