In a long-running Berkeley study, researchers found that women who smiled genuinely in their college yearbook photos went on to have more stable marriages and higher wellbeing thirty years later than those whose smiles were posed - Silicon Canals

What the report says

A 2001 study of 141 women photographed for the 1960 Mills College yearbook found that those with genuine, eye-crinkling smiles reported better marital and personal outcomes thirty years later. A careful reading of what the finding does and does not support.