You've probably seen it before-two elderly people walking hand in hand down the street and looking very much like each other. They look so much alike that they could be brother and sister. Do you believe that people who live together for many years would look alike? It's strange. but scientists say it's true. How scientists proved it? In a study, scientists found young couples only showed similarity by chance. However, elder couples were very likely to look like each other. The similarity could be very subtle  and could be found in wrinkles  or furrows, etc. Besides, some couples look far more alike than other couples. The scientists thought of several possible reasons: 1. Diet. "We are what we eat." As couples usually share the same diet, will they probably look alike? For example, if both partners eat a high fat diet, their faces will tend to look fat. However, the scientists ruled this out  using another small study. 2. Environment. Will elderly couples show similarity because they live together in the same area for a long time? The environmental factors  such as sunshine and wind affect the skin in similar ways. The scientists ruled this possibility out as well. 3. Empathy . This is the theory  the scientists believe in. Couples grow to look similar because they are empathizing with each other. They copy each other's facial expressions. For example, if one partner often smiles in a certain way, the other is likely to copy it. In this way, their faces share similar wrinkles and furrows. Which is the theory the scientists believe in?
Empathy. Diet. Environment. Wrinkles.