Science of Grays- Your hair follicles have pigment cells that make melanin, a chemical that gives your hair its color. As you age, these cells start to die. Without pigment, new hair strands grow in lighter and take on various shades of gray, silver, and eventually white. Once a follicle stops making melanin, it wonβt make colored strands again.When and Why It Happens You might blame your stressful job or your unruly teens for your grays. But it is mostly your genes that dictate how early and how quickly it happens. So if either of your parents had a full head of gray hair in their 30s, there is a good chance you will, too.