Thanks to the annual "Twins Days Festival" in Twinsburg, Ohio, researchers at Case Western Reserve University were able to verify what many health professionals had long theorized -- that smoking cigarettes promotes premature aging of the face.

The study, "designed to examine the aging effects of smoking on the faces of identical twins," selected 79 sets ranging in age from 18 to 78 with the mean age being 48. In some of the sets, only one sibling smoked, if both did, one would have to have smoked for at least five years longer than the other in order to participate.

READ: The 7 Sneaky Ways Smoking Steals Your Beauty

The twins completed medical and lifestyle history questionnaires ("The twin pairs were similar in other environmental factors that can affect facial aging, including sunscreen use, alcohol intake, and work stress.") and had professional photographs taken of their faces. Then, with no knowledge of the participants' histories, plastic surgeons examined the photos and found remarkable differences between the twins.

According to the Journal of the American Society of Plastic Surgeons, which reported the findings, "Scores on several measures of facial aging were significantly worse for the smokers. The smokers had more sagging of the upper eyelids, as well as more bags of the lower eyelids and under the eyes. Twins who smoked also had higher scores for facial wrinkles, including more pronounced nasolabial folds (lines between the nose and mouth), wrinkling of the upper and lower lips and sagging jowls."

Interestingly, although not necessarily surprising, most of the facial differences were found in the lower third of the face -- around the mouth.

Does these findings come as a revelation to you or have you long thought that smoking would be a cause for premature aging?

READ: 5 Sneaky Ways Alcohol Affects Your Health and Beauty