How environment and lifestyle choices influence the aging process.

Differences in the physical appearance of identical twins attributable to aging were studied. Because these individuals are identical genetically, any differences found were believed to result from external factors. Twins showing the greatest discrepancies in visible aging signs also had the greatest degree of discordance between personal lifestyle choices and habits. The most notable exogenous factors influencing degree of aging were sun exposure and smoking. Other possibly contributory lifestyle factors include alcohol consumption, stress, diet, exercise, disease, and medication. In summary, the genetic influences on aging may be highly overrated, with lifestyle choices exerting far more important effects on physical aging.