Why couples start to look alike

It’s folk wisdom that couples in long and happy relationships look more and more alike as the years go by. Peer closely at those old photographs, and you’ll see that the couples haven’t actually grown similar noses or chins. Instead, they have reflected, each other’s expressions so frequently and so accurately that hundreds of tiny muscle attachments to their skin have reshaped their faces to mirror their union. How this happens gives us a window on one of the most fascinating recent discoveries about the brain, and about how we come to “feel felt” by one another. 

 Daniel J. Siegel, Mindsight