Your hair colour is determined by your genes. These genes have been passed down from your parents and their ancestors. Although for the most part your hair colour is a hereditary trait, some exceptions that are associated with disease or congenital anomalies can cause a change in your hair colour.
Understanding that your hair colour is determined by your genes is only the beginning. Scientists are continually studying the mechanisms that genes and regulatory molecules use to send signals telling hair follicles what colour to produce a hair. Similar molecular controls are also used to determine the pigmentation of skin. Therefore, it makes sense that a fair-skinned person will have lighter hair and a dark-skinned person will have darker hair. All hair can lose pigmentation and become grey or white as people age.
Melanocytes are responsible for genetic signalling that controls skin and hair pigmentation. These are specialized cells that are found in hair follicles and the skin. As the name suggests, a melanocyte’s purpose is to synthesize the pigment melanin. Melanin is what gives colour to our hair and skin.
Melanosomes are sub-cellular organelles that are found in melanocytes. These are what create melanin. There are 2 types of melanosomes: elliptical or oval-shaped melanosomes that specialize in creating brown and black eumelanin and sheroidal or round melanosomes that create yellow and red pheomelanin.
Colour is not produced in the hair shaft in the earliest stages of hair growth. Therefore, the tip of a newly formed hair is colourless. As the hair grows and continues developing in the hair follicle, pigment enters the core of the shaft, which is found under the protective layer of keratin.
Grey hair is created when the melanocytes start to become inactive and the creation of melanin dwindles. Once no more melanin is produced, white hair is produced. White is the absence of colour.
We are not there yet, but we may soon be able to alter our hair colour genetically as well as stop the aging process that turns our hair grey or white.