Here's why:

* "Poly" means "many"

* "Genic" refers to genes

So, a polygenic trait is one that is determined by the combined effects of multiple genes, rather than just one. This means that the trait can have a wide range of variations, and the expression of the trait is influenced by the interaction of these multiple genes.

Examples of polygenic traits:

* Height: Many genes contribute to a person's height, resulting in the wide range of heights we see in humans.

* Skin color: Multiple genes are involved in determining skin pigmentation, leading to the variety of skin tones we observe.

* Intelligence: Intelligence is a complex trait influenced by numerous genes and environmental factors.

* Weight: Many genes and lifestyle factors contribute to an individual's weight.

Polygenic traits are often influenced by environmental factors as well. For example, even though genes play a role in height, factors like nutrition and health can also influence an individual's final height.