What does sunburn, smoking and excess weight have in common? It may come as a surprise to learn that all can damage your skin—making you look older than you really are. Researchers at Case Western Reserve Medical School in Cleveland arrived at this conclusion after studying 65 pairs of identical and fraternal twins who attended the 2002 Twin Days Festival in Twinsburg, Ohio. “The Twins Days Festival provides a rare opportunity to study a large number of twin pairs to control for genetic susceptibility,” the study authors wrote.

The twins, who ranged in age from 18 to 77, answered questions about their weight, skin type, smoking and drinking habits, and history of skin cancer. Each participant was assigned a photodamage score, which graded characteristics such as wrinkling and pigmentation changes. The researchers found that skin damage was similar among the twins whether they were identical or fraternal, which suggests that “people with the same genetic composition are more likely to have the same sort of sun damage,” said Dr. Jonette Keri, an assistant professor of dermatology at University of Miami Miller School of Medicine. In other words, “if your mom aged poorly, you are going to age poorly,” she said.

However, up to 40 percent of aging-related skin changes are due to non-genetic factors, the researchers noted. Age, smoking, and a history of skin cancer were all associated with higher levels of photodamage. In fact, the skin cancer rate among the twins was found to be higher than in the general population, a finding that surprised Dr. Jeffrey Salomon, an assistant clinical professor of plastic surgery at Yale University School of Medicine who was not involved in the research. “This study, with an 8 percent skin cancer rate in twins, seems high when the general population has an incidence of less than 0.5 percent. This in of itself would merit further examination to look at other (potential risk) factors, such as prenatal x-rays, prenatal sonograms and low birth weights,” he said.

Cigarette smoking has long been recognized as a cause of wrinkles. And though smoking-related wrinkles may not appear for a decade or more after the first puff, damage to the connective tissue, which is the basis for the skin’s smooth appearance, occurs with every cigarette smoked. “Cigarette smoke induces matrix metalloproteinases in the skin and inhibits procollagen synthesis through alteration of transforming growth factor beta,” the researchers explained. The combination of smoking and sun exposure is particularly toxic.

Heavier weight was also found to be linked to photodamage, the researchers say, although a study of Danish twins concluded that higher body mass index was associated with less facial aging. Keri said the overweight-wrinkle connection isn’t as obvious because even though excess weight may increase the skin’s susceptibility to damage, it often masks the appearance of wrinkles in older people. “They won’t look as wrinkly because the fat on their face is plumping out their skin,” she said.

On the other hand, alcohol consumption was associated with having less photodamage. The researchers explained this may be due to the fact that some types of alcohol, such as red wine, contain polyphenols that are effective antioxidants, such as resveratrol, which may help preserve the skin.

The most common signs of skin damage include dry, scaly skin; skin with a yellow, leathery appearance; broken capillaries; fine, coarse wrinkles or pigmentation problems. Sun spots, also known as liver or age spots, are flat brownish colored patches that appear on the body, most often on the face, arms and hands. The researchers say they hope people will use the study findings to change their behaviors and prevent excessive skin damage from controllable environmental factors. “The relationships found between smoking, weight, sunscreen use, skin cancer and photodamage in these twin pairs may help to motivate the reduction of risky behaviors,” they wrote.

The study findings are published in the December issue of the Archives of Dermatology.