You can slather on as much sunscreen and buy as many anti-aging creams as you want, but how well your skin ages over time might depend on factors beyond your control—like your blood type. In fact, new research notes that your blood type, of all things, may play a big role in your susceptibility to wrinkles.

In a recent study from the Annals of Dermatology, researchers analyzed the skin of Korean women aged 66 to 84: 29 with type A blood; 26 with type B; 31 with type O; and 13 with type AB. After measuring the wrinkle depth and elasticity around the participants’ eyes, as well as their skin color—including their levels of melanin, the darkening pigment that causes your skin to tan when exposed to the sun—they found that people with a B blood type produced less melanin and had deeper wrinkle formation. But why?