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  • Tracy Spring

The Twin Study: Factors that accelerate facial aging

Nature Versus Nurture

Identical twins have identical genetic programming. If lifestyle had no impact on aging, twins would age at the same rate. Differences in lifestyle and environment have long been suspected of influencing the pace at which we age, and a study published in Plastic and Reconstructive Surgery by Guyuron et al. (2009) confirms this. Researchers surveyed and photographed 186 sets of identical twins, and an independent panel analyzed the photos. Several factors were then correlated with the perceived age differences.

Photo credit: ASPS, PRS Vol. 123 number 4. The facial features evaluated to determine the perceived age difference between twins in the Guyuron et al. study.

The study confirmed the influence our way of life has on aging. Differences in appearance made one sibling look older than the other. These differences were attributed to contrasting behaviors and environments. This research proved that certain choices we make in our day to day life have the potential to keep us looking younger longer.

What were the secrets of the younger looking twin?

Sun Exposure

UV rays are harmful to our skin; causing spots, wrinkles, and even cancer. Though if there was ever any doubt, this study provides strong evidence in support of these warnings. Sun exposure was the number one reason the panel perceived a difference in age between twins.

Each woman revealed the approximate amount of time she had spent in the sun since childhood. As predicted, the twin who had spent more time in the sun had deeper wrinkles and more spotting or discoloration of the skin. Women who reported using sunscreen minimized damage to their skin and collagen.

Photo Credit: ASPS, Vol 123 number 4 The panel determined that Twin B (right) looks 11.25 years older than Twin A (left). They are both 61 years old here. Twin B had approximately 10 hours more per week of sun exposure than Twin A. Additionally; Twin B weighs fifteen pounds less than Twin A. (Continue reading to learn how weight impacts the appearance of age.)

Photo Credit: ASPS, Vol 123 number 4. These twins are 69 years old. The perceived age difference between them was 3.375 years. Twin A (left) had about 19 hours per week more sun exposure than Twin B.

Bottom line: The twin who reported having the most sun exposure appeared older than their twin sibling.


Weight has a definite impact on perceived age, according to the study. French actress Catherine Deneuve famously said, "After a certain age, you have to choose between your fanny and your face." She observed that as we age being very thin can cause the face to look haggard or gaunt, whereas a few extra pounds can fill out lines and soften wrinkles. Researchers were able to confirm this to be true for women over the age of forty. However, for women under forty, they observed the opposite to be true: extra weight can cause youthful attributes like a smooth, defined jawline to become obscured, plus extra pounds can cause skin to look saggy.

Relevant differences in the twins due to weight were noticeable when there was at least a twenty-pound disparity between the women. After age fifty-five, a forty-pound difference in body weight was required for the heavier twin to appear younger.

Lead researcher Dr. Guyuron clarified that he wasn't encouraging people to put on weight or to remain overweight. It was merely a factor they observed that impacted appearance.

Photo Credit: ASPS, Vol 123 number 4. 58-year-old twins: the panel determined that Twin A (left) appeared 5.25 years younger than Twin B (right). Twin A weighed about 75 pounds more than twin B (a 14.7 higher BMI value). There were no other relevant differences in lifestyle.

Photo Credit: NBC These twins are 27 years old, and Twin A (left) weighs 50lbs less than Twin B (right). Twin A looks younger, predominately due to the definition in her cheekbones and jaw that is obscured in her heavier twin. (Data for the perceived age difference unvailable.)

Bottom line: Twins under forty with a higher BMI than their sibling looked older, while twins over forty with a higher BMI than their sibling looked younger. After age fifty-five a twin had to weigh forty pounds more than their sibling to appear noticeably younger. 

These findings support the use of dermal fillers to increase facial volume for facial rejuvenation.

BMI point is equal to about 5 or 6lbs. So, four BMI points equal 20-24lbs.

Marital Status

Surprisingly, marital status seemed to influence the appearance of the twins. On average, the panel perceived divorced women as 1.7 years older than their twin who was either married or single. Since stress has been known to accelerate the aging process, it was speculated that stress or depression might be to blame. One would think losing a spouse would be a source of stress, but widowed twins appeared two years younger than their sibling on average. The researchers had no explanation for this finding.

Photo Credit: NBC Twin B (right) looks older than Twin A (left), according to the panel. (Actual age 54.) Researchers concluded that divorce (after 27 years of marriage) was the culprit for Twin B's older perceived age. Twin A has been married for more than thirty years. No other relevant factors differed for this set of twins. (Data for the perceived age difference unavailable.)

Bottom line: Divorced twins were perceived as older than their married or single twin. Widowed twins were regarded as younger than their non-widowed twin.


A sibling with a history of smoking was perceived as two and a half years older than their non-smoking sibling for every decade that they smoked. The twin with a history of smoking must have smoked for at least five years for there to be a perceptible difference in appearance.

Dr. Guyuron said that "smoking reduces collagen formation, results in collagen degradation and reduces the skin circulation." He also explained that nicotine reduces the thickness of the skin and reduces skin elasticity.

Photo credit: ASPS, Vol. 123 number 4. 52 years old twins: Twin A (left) smoked for 20 years longer than Twin B (right). The perceived age difference here was 6.25 years. Dr. Guyuron explains that the bags under Twin A's eyes are due to her long-term smoking habit. Twin A also reported seven times the sun exposure of her twin sister and weighed less as well. (Data for weight difference unavailable.)

Photo credit: ASPS, Vol. 123 number 4. These twins are 57 years old. Their perceived age difference is 8.25 years. Twin B (right) looks older because she smoked for 40 years (Twin A on the left is a non-smoker). Also, Twin A had four years of hormone replacement therapy. (Continue reading to find out how hormone replacement impacts perceived age.)

Bottom line: Twins who smoked five years or more looked older than their non-smoking twin, and smoking twins looked about two and a half years older than their non-smoking twin for every decade that they smoked.


The use of antidepressant medication was associated with an older appearance. Dr. Guyuron explained that certain antidepressants weaken eye muscles over time, which could cause the eye area to become droopier. It is also thought that sadder facial expressions due to depression could be partly to blame. (No images were available of twins who had a difference in perceived age due to antidepressant use.)

Bottom line: Twins who took antidepressants appeared older on average than their twin sibling who did not.

Birth Control/Hormone Replacement Therapy

Hormone-replacement therapy or birth control pills can pose health risks in addition to having several benefits. One such benefit is that estrogen improves skin elasticity and can help smooth out the skin by increasing water retention.

The study found that the longer a woman was on birth control pills or used hormone-replacement therapy, the more likely she was to appear younger.

Estrogen begins to decrease when a woman enters menopause, and hormone-replacement therapy can help counteract this.

Photo credit: ASPS, Vol. 123 number 4 These twins are 71 years old. Their perceived age difference was 7.25 years. Twin B (right) had 22 more years of hormone replacement therapy than Twin A, making her appear younger.

Bottom line: Twin siblings who took birth control or used hormone-replacement therapy were judged to be younger than their twin sibling who did not.


Not surprisingly, the excessive intake of alcohol will rapidly accelerate premature aging. It can also damage blood vessels in the skin. Dr. Guyuron explained that the liver has a lot to do with both the quantity and quality of the collagen fibers. The study confirmed the adverse effects alcohol has on appearance. (No photos were available of twins who had a difference in perceived age due to alcohol use.)

Bottom line: Twins who reported greater alcohol intake overall appeared older than their twin who consumed less or no alcohol.


Another "twin study" of interest is one on preventative Botox. It was done in 2006 by William J. Binder, MD and showed that long-term treatment with Botox prevents static lines from forming (lines that are visible when your face is not animated).

For this study, one twin received Botox in the forehead and glabellar region (between the eyebrows for "frown lines") two to three times yearly for thirteen years and for crow's feet twice in the two years before these photos. The other twin received Botox only twice (in the forehead and glabellar region, three and seven years before these photos).

Photo Credit: Archives of Facial Plastic Surgery, Nov/Dec 2006. Twin A (left) did not have regular preventative Botox treatments, while Twin B did. (Twin B had Botox 2-3 times a year for 13 years.) Notice the forehead area especially.

Photo Credit: Archives of Facial Plastic Surgery, Nov/Dec 2006. Twin A (left) did not have regular Botox, and Twin B (right) did for thirteen years.

Photo Credit: Archives of Facial Plastic Surgery, Nov/Dec 2006. Twin A (left) did not have regular Botox, and Twin B (right) did for thirteen years. Notice the area at the corner of the eyes.

Bottom line: The twin who was treated 2-3 times a year for thirteen years with Botox had noticeably smoother skin with fewer imprinted wrinkles than her twin sibling who was not treated regularly.

In summary

The first study by Guyuron et al. provides strong statistical evidence that many of the factors previously blamed for accelerating aging are indeed guilty of doing just that. It also illuminates previously unrecognized factors that hasten the appearance of aging. Both studies demonstrate that there are things we can do (or not do) to look younger longer. It appears “nurture” may override “nature” when it comes to the visible progression of aging.


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