Looking in the mirror, you probably see features from both of your parents (and possibly the milkman). Perhaps you have your father's eyes and nose, but your mother's ears and lips.
Scottish scientists have discovered that your face contains other subtle family clues -- your childhood socioeconomic status. Researchers found that to some degree people's early home life is detectable in their faces more than 70 years later.
In the study, published in the journal Economics and Human Biology, scientists looked at 292 older adults who participated in the Lothian Birth Cohort 1921, a long-term research trial of Scottish children born in 1921 that tracks their health across a lifetime.
Researchers wanted to see if the participants, who were now octogenarians, showed traces of their early upbringing in the symmetry of their faces or their bodies.
To determine this, volunteers first completed questionnaires about their family's economic circumstances at age 11, including information about each parent's occupation, the number of family members living at home and sleeping in each room, and whether they had indoor plumbing. Participants were also asked about the job they held in middle age to determine the social class they attained as adults.
At age 83, they measured each person's facial symmetry from a photograph by comparing the left and right sides for 15 pairs of facial features, such as the positions of the eyes, ears, mouth, and nose. More attractive people typically have more symmetrical faces and less facial symmetry may occur because of higher levels of stress, infections, toxins, or possibly genetic differences.
At age 87, researchers measured body symmetry at 14 locations, including finger lengths, ankle, wrist, and elbow widths, and height of the ears.
Scientists found a link between early life deprivation and facial -- but not body -- symmetry. This association, although weak, was stronger in men than in women.
Researchers suggest that early environmental factors, such as childhood nutrition, illness, and parent's smoking and alcohol habits, can affect a child's health and development by leaving a lasting impression on the face. Men with poorer beginnings tended to have more asymmetrical features in older age -- despite improving their social standing as adults.
"Our results show that symmetrical faces reflect better social and economic circumstances," says Timothy Bates, a professor of individual differences in psychology at the University of Edinburgh, and one of the study's co-authors. "But we don't know the specific elements of these desirable circumstances that lead to more symmetrical development," he adds.
Bates says the research team was surprised to find the influence of social status on symmetry was restricted to childhood, and that body symmetry was resilient to early life deprivation.
"We think this is because body symmetry is more reflective of processes that are protected in development, whereas the softer facial features are more plastic and reflect stress to a greater degree," Bates explains.