Dr Tony Little, from the University's School of Biological Sciences, explains: "There is widespread belief that couples, particularly those who have been together for many years, look similar to each other. To understand why this happens, we looked at the assumptions that people make about a person's personality, based on facial characteristics. We found that perceptions of age, attractiveness and personality were very similar between male and female couples. For example if the female face was rated as 'sociable' then her partner was also more likely to be rated as 'sociable.'

"We also found that couples who had been married for a long period of time, were perceived as having more similar personalities than those who had not been together very long. This may come from sharing experiences together - affecting how their face appears."