While 60 percent of our skin’s aging is prewritten in our genetic code, the rest is up to us. In a comparison of 144 pairs of identical twins, researchers found that smoking, sun exposure, BMI and other factors can age us, genes be damned. So good habits, like saying yes to sunscreen and no to cigarettes, can make a major difference in how young you look.

MORE: Genes vs Routine: How to Control Your Skin Aging