HESI A2 Biology Practice Test

Polygenic inheritance refers to the phenomenon where a trait is influenced by multiple genes, each contributing to the overall phenotype in a cumulative manner. This means that rather than being controlled by a single gene, traits such as height, skin color, and intelligence may be the result of the additive effects of several genes, often resulting in continuous variation within a population. Each contributing gene may have a small effect, and the combination of many such genes leads to the diverse expressions of the trait observed.

For example, in human height, various genes contribute to the overall height measurement, and the interaction between these genes and environmental factors can lead to a wide range of heights in the population. This complex inheritance pattern is foundational in understanding traits that do not follow simple Mendelian inheritance, where a single gene would typically determine a specific trait.