Skin and hair color are both what we call polygenic features: they depend on a bunch of different genes working together, with more still being discovered. To make things worse, two people can have all of the same genes but still have different hair colors!
Yes, hair color is a polygenic trait. Some other polygenic traits are human skin, eye color. These are polygenic traits because they are regulated by more than one allele at different loci. Polygenic inheritance takes place when one trait is regulated by two or more genes.
The term polygenic means “many genes.” Therefore, a polygenic trait is influenced by many genes that work together to produce the phenotype. Human phenotypes such as hair color, eye color, height, and weight are examples of polygenic traits.
Skin color is also a polygenic trait, as are hair and eye color. Polygenic inheritance often results in a bell shaped curve when you analyze the population (Figure below).
A polygenic trait is a characteristic, such as height or skin color, that is influenced by two or more genes. Because multiple genes are involved, polygenic traits do not follow the patterns of Mendelian inheritance. Many polygenic traits are also influenced by the environment and are called multifactorial.
Hair color is one of several physical traits that are genetic, or passed down through an individual's DNA. Human DNA has millions of on and off switches along networks that control how genes function. Genes responsible for hair color come from both parents.
Usually, traits are polygenic when there is wide variation in the trait. For example, humans can be many different sizes. Height is a polygenic trait, controlled by at least three genes with six alleles. If you are dominant for all of the alleles for height, then you will be very tall.
Polygenic trait refers to a trait that is controlled by multiple non-allelic genes. These genes are called polygenes. They are a group of genes that, when turned on, are expressed as a unit. Each of them produces an effect that adds up to the trait.
Whilst red hair is essentially a Mendelian trait modified by additional loci, the genetic architecture of blonde hair colour is concordant with a polygenic trait.
Polygenic inheritance refers to a single characteristic that is controlled by more than two genes (also called multifactorial inheritance)
Single-Gene Traits: The allele for black color might become more common. Polygenic traits have a range of phenotypes that often form a bell curve. The fitness of individuals may vary from one end of the curve to the other. Natural selection can affect the range of phenotypes and hence the shape of the bell curve.
Some examples of polygenic inheritance are: human skin and eye color; height, weight and inteligence in people; and kernel color of wheat.