When men and women look like

When people live or work together for a long time, they often become similar. This is because they constantly copy each other’s facial expressions. Over time, the facial muscles remember the usual expression. Even those who are physically dissimilar to each other, in the photos look very similar, because they smile exactly the same.

David and Victoria Beckham are unlike each other, but only until they smile	Forty Years of Permanent Copy: Beckham's retired couple with their dog Spot

In 2000, psychologist John Gottman of the University of Washington in Seattle and his colleagues found that the marriage would almost certainly fall apart if one of the partners not only does not copy the expression of happiness on the other’s face, but also responds with an expression of irritation and anger. Such behavior affects a smiling partner, even if he is not aware of this.