Why is my hair brown?

The presence or absence of a substance called melanin is what determines the different hair colors.  For brown hair, a subdivision of melanin, called eumelanin, is what produces the pigment, or color, for brown hair.  There are is a eumelanin for brown hair, then one for darker hair, such as black hair.  A lighter eumelanin is the substance responsible for blonde hair.  Hair color is determined largely by heredity, which is the passing of physical traits from parents to offspring.  One or both of your parents passed the genes for brown hair on to you when you were conceived by your mother.  Environment is another thing that can have something to do with the promotion of darker hair, such as brown hair.  People who live in areas with warmer climates, closer to the equator, tend to have both darker skin and darker hair.