The story of your life really is written on your face, according to new research by scientists.
In some people, the weather-beaten skin and deep lines that crease their face betray obvious clues about the hard life they have led, but now scientists have discovered everyone's facial features may betray their childhood.
Scientists at the University of Edinburgh have found it is possible to learn about a person's childhood by looking at how symmetrical their face is.
Using 15 different facial features, they found that people with asymmetric faces tended to have more deprived childhoods and so harder upbringings than those with symmetrical faces.
Their findings suggest that early childhood experiences such as nutrition, illness, exposure to cigarette smoke and pollution and other aspects of a difficult upbringing leave their mark in people's facial features.
Surprisingly, their facial features were not affected by their socioeconomic status in later life, which suggests that even those who manage to undergo a rag-to-riches transformation can never escape their past as it will be written on their face.
It may explain why celebrities such as Gordon Ramsay and Tracey Emin, who had difficult and impoverished childhoods, have such distinctive asymmetric facial features despite having since amassed personal fortunes.
Professor Ian Deary, from the department of psychology at the University of Edinburgh's centre of cognitive ageing, said: "Symmetry in the face is thought to be a marker of what is called developmental stability – the body's ability to withstand environmental stressors [stress factors] and not be knocked off its developmental path.
"We wondered whether facial symmetry would faintly record either the stressors in early life, which we though might be especially important, or the total accumulated effects of stressors through the lifecourse.
"The results indicated that it is deprivation in early life that leaves some impression on the face. The association is not very strong, meaning that other things also affect facial symmetry too."
Professor Deary and his colleagues examined the facial features of 292 people aged 83 who took part in the Lothian Birth Cohort 1921, a study that has followed the participants through out their lifetime.
They were able to compare the facial symmetry of the participants to detailed information about their social status at childhood, including their parent's occupation, how crowded their home was and whether they had an indoor or outdoor lavatory.
They examined 15 different "landmarks" on the face, including the positions of the eyes, nose, mouth and ears.
They found there was a strong association between social class and the symmetry of the face in men. Those with more symmetrical faces had more privileged and easier upbringings than those with asymmetrical features.
The results in women were less strong and the researchers want to carry out further studies with other facial markers that may give a stronger association.
The researchers, however, found no correlation between participants social status in later life and their facial features.
Professor Tim Bates, who co-authored the study, added: "A small link from parental status to facial symmetry doesn't mean people are trapped by their circumstances. Far from it – as shown by the high levels of mobility in society, not just people like Gordon Ramsay, but to lesser degrees by millions of people."
The link between facial symmetry and exposure to stress in early life might explain why many studies have found that people with symmetrical faces are considered to be the most attractive.
Lop-sided facial features may unconsciously provide a signal that a person is less desirable as a mate due to the stress they experienced in early life which could leave them vulnerable to disease and premature death.
In their study, which is published in the journal of Economics and Human Biology, the scientists suggest that facial symmetry could be used alongside medical markers such as high blood pressure to identify people who might be at an increased risk of disease.
Professor Dearly, however, insisted there was still a lot of work to do before it could be used like this.
"It is a research-based measure and quite tricky to calculate at present," he said.