Why does some body hair turn grey but not others?

Body hair turns grey primarily due to a decrease in melanin production as people age. The hair follicles gradually lose their pigment-producing cells, leading to the loss of color. However, not all body hair may turn grey at the same rate or at all, as different hair types and follicles can have varying sensitivities to aging and genetic factors. Additionally, the distribution and density of pigment cells in different hair regions can also influence whether certain hairs turn grey.