Just like the color of your eyes and hair, the natural tint of your teeth is hereditary. “Some people have very white enamel — the thin coating on the surface of teeth — while other people’s enamel has a more yellow hue,” says Richard Price, a dentist in Newton, Massachusetts, and a spokesperson for the American Dental Association. Environmental factors play a role, too. “Teeth are kind of like the rings on a tree,” Price says. “They tell a lot about a person’s health and history.” Taking the antibiotics tetracycline or amoxicillin as a child can affect the calcification process, causing discoloration. Certain foods can also darken teeth. “If a substance will stain a carpet,” Price says, “it will stain your teeth.” Coffee, tea, cola, and red wine are common culprits. Frequent cleanings can help, but severe food stains may require a whitening product or procedure.