Hair turns grey as you age primarily due to a natural and gradual decrease in the production of melanin, the pigment responsible for the color of your hair, skin, and eyes. Melanin is produced by melanocytes, which are cells located in the hair follicles. There are two main types of melanin: eumelanin, which is responsible for black or brown colors, and pheomelanin, which contributes to red and yellow colors.

As you age, the melanocytes gradually become less active and eventually stop producing melanin. This reduction in melanin production leads to the loss of color in the hair, resulting in grey or white hair. The specific timing and rate of this process can vary among individuals and are influenced by factors such as genetics, hormonal changes, and environmental factors.

Genetics play a significant role in determining when and how quickly your hair will turn grey. If your parents or grandparents experienced early greying, there is a higher likelihood that you may also start to grey earlier in life.

Hormonal changes, such as those associated with aging, can also influence the color of your hair. Additionally, factors like stress, smoking, and certain medical conditions may contribute to premature greying.

While the graying of hair is a natural part of the aging process, it's important to note that individual experiences can vary, and not everyone will experience grey hair at the same rate or in the same way.