What contributes the most to skin aging?

Genetics.: Other than genetics (which we can't control), smoking, sun exposure, and weight gain/loss are the most damaging factors. Good general health can help avoid skin and aging problems associated with disease conditions and chemotherapy, for example, but these too are often outside our control. Dr. Tholen.

Common factors seen: Are long term smoking and extensive sun damage. Heredity and luck also play a role, but we have no control over these.

Sun: Sun, stress, and smoking.