A gene linked to pale skin and red hair might also influence the way our faces age, new research suggests.
Dutch and British biologists studied the DNA of 2,693 people and then asked 30 volunteers to judge their age based on photographs.
They believe their research, published in Current Biology, may have identified the MC1R gene as influencing how appearance is affected by age.
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Their study indicates that white Europeans who possess two copies of variant forms of the MC1R gene appear as much as two years older than those who don't. People with one copy of the gene looked up to one year older on average.
Pale skin, which has proven links to MC1R, is already associated with more noticeable aging as it is more vulnerable to sun damage. However, even allowing for factors such as skin tone, the gene still appeared to have the same influence on the subject's perceived age.
"Combined with other factors such as sun exposure and smoking, genetic factors could make a sizable dent in the youthfulness of one's appearance," Scientific American reports.
Scientists have long held that the way a person's physical appearance corresponds to their actual age is influenced by a combination of genetic and environmental factors, but MC1R is the first gene to be specifically linked with the aging process.
However, some scientists have expressed doubts about the method in which the study was carried out. Ian Jackson, a geneticist at Edinburgh University, explained the dilemma to The Guardian: "Are you really measuring how old people look, or are you measuring the psychology of the observer?"
The study's co-author, forensic molecular biologist Manfred Kayser, also warned those eager to ascribe their haggard appearance to genetics that the difference was too small to be significant on its own.
"If you now want to use this to blame your genes for looking much older, it won't work," he said.
