Answer:
Mainly, the number of genes that control traits.
Explanation:
Polygenic inheritance does not follow Mendel's law of dominance. According to Mendel the dominant trait will mask the recessive trait however, this is not always the case. Polygenic inheritance states that traits are controlled by two or more genes and is also dependent on the environment.
Let's take skin color for example. A fair-skinned person will have a child with a dark-skinned person.
Mendelian inheritance would assume that the offspring would either be fair or dark only.
Polygenic inheritance would assume that the offspring would be either fair, dark, or a tone in between, depending on the environment they are in as well.
Hope you understood it.
