Aging is attributed to both intrinsic and extrinsic processes. Photoaging, characterized by coarse wrinkling, hyperpigmentation, hypopigmentation, and telangiectasia, is the most recognized form of extrinsic aging. Intrinsic aging is characterized by finely wrinkled skin, cherry hemangiomas, and seborrheic keratoses. The study of twins provides the opportunity to control for genetic susceptibility. In this survey and clinical evaluation of twins at the annual Twins Days Festival in Twinsburg, Ohio, Martires et al demonstrate that environmental and genetic factors affect photoaging and skin cancer development. Weight and alcohol intake were correlated negatively with photoaging, whereas cigarette smoking was associated with marginally greater photodamage.