Non-Mendelian genetics encompasses various inheritance patterns that do not conform to Gregor Mendel's laws. One significant aspect of this is polygenic inheritance, which refers to traits influenced by multiple genes. The term "polygenic" combines the prefix "poly," meaning many, with "genic," relating to genes. Thus, polygenic traits are single phenotypic characteristics that result from the interaction of several genes.
For instance, human height is a classic example of a polygenic trait, as it is determined by over 180 different genes. This complexity illustrates how a single trait can be influenced by multiple genetic factors, contrasting sharply with Mendelian traits, which are typically governed by a single gene. In the case of height, variations can be observed across a spectrum, such as individuals measuring 6 feet 5 inches, 6 feet, 5 feet 5 inches, and 5 feet, all of which highlight the continuous nature of polygenic traits.
Understanding polygenic inheritance is crucial as it lays the groundwork for exploring other genetic concepts, such as pleiotropy, where a single gene can affect multiple traits. This complexity in genetic inheritance patterns emphasizes the intricate relationship between genes and phenotypes in living organisms.