"Pictures of grinning kids may reveal more than childhood happiness: a study from DePauw University shows that how intensely people smile in childhood photographs, as indicated by crow’s feet around the eyes, predicts their adult marriage success. According to the research, people whose smiles were weakest in snapshots from childhood through young adulthood were most likely to report being divorced in middle and old age. Among the weakest smilers in college photographs, one in four ended up divorcing, compared with one in 20 of the widest smilers. The same pattern held among even those pictured at an average age of 10.
The paper builds on a 2001 study by psychologists at the University of California, Berkeley, that tracked the well-being and marital satisfaction of women from college through their early 50s. That work found that coeds whose smiles were brightest in their senior yearbook photographs were most likely to be married by their late 20s, least likely to remain single into middle age, and happiest in their marriage; they also scored highest on measures of overall well-being (including psychological and physical difficulties, relationships with others and general self-satisfaction)."
This article was in a recent issue of Scientific American.