At age 61, identical twins Jeanne and Susan no longer look exactly alike. Susan smoked for many years and is an admitted sun worshipper, whose habits Jeanne does not share. A new study of twins suggests you can blame those coarse wrinkles, brown or pink spots on too much time in the sun, smoking, and being overweight. Because twins share genes, but may have different exposures to environmental factors, studying twins allows an "opportunity to control for genetic susceptibility ," Dr. Elma D. Baron, at Case Western Reserve School of Medicine in Cleveland, Ohio, and his colleagues explain in the latest issue of Archives of Dermatology. Their analysis of environmental skin-damaging factors in 65 pairs of twins hints that skin aging is related more to environment and lifestyle than genetic factors. But when it comes to skin cancer, the researchers say their findings support previous reports that both environment and genes affect skin cancer risk. Baron's team examined facial skin of 130 twins, 18 to 77 years old, who lived mostly in the northem Midwest and Eastern regions of the US, who were attending the Twins Days Festival in Ohio in August 2002. At this time, each of the twins also separately reported how their skin burned or tanned without sunscreen, their weight, and their history of skin cancer, smoking, and alcohol drinking. The study group consisted of 52 fraternal and 10 identical twin pairs, plus 3 pairs who were unsure of their twin status. From these data, the researchers noted strong ties, outside of twin status, between smoking, older age, and being overweight, and having facial skin with evidence of environmental damage. By contrast, sunscreen use and drinking alcohol appeared related to less skin damage. Baron and his colleagues say the current findings, which highlight ties between facial aging and potentially avoidable environmental factors--such as smoking, being overweight, and unprotected overexposure to the sun's damaging rays--may help motivate people to minimize these risky behaviors. The passage is mainly concerned with _ . A) skin cancer and environment B) identical twins research C) aging skin and environmental factors D) genes and lifestyles
The answer to this question is:
C