Read this neat NYT write-up of new research by Nancy Segal and co-authors. Segal, famous for her work on twins, got an idea when she encountered the oeuvre of Francois Brunelle, "a photographer in Montreal who takes pictures of pairs of people who look alike but are not twins":
When [Segal] saw the photographs, she realized
that the unrelated look-alikes would be ideal study subjects: She could
compare their similarities and differences to those of actual twins.
For Dr. Segal's initial study,
she asked Mr. Brunelle to send questionnaires to some of his subjects,
and she received completed forms from 23 pairs of unrelated look-alikes.
The questionnaires yield a score based on five personality measures:
stability, openness, extroversion, agreeableness and conscientiousness.
The participants also took the Rosenberg Self-Esteem Scale...
For a second study,
she teamed with a skeptic, Ulrich Ettinger, a psychologist at the
University of Bonn in Germany who had heard about the look-alike project
during a postdoctorate at the University of Montreal.
thought that if two people looked alike, they would have similar
personality traits because people would treat them the same," he said.
"For example, I thought men who looked alike and were tall and handsome
would probably be extroverts."
analysis was consistent with the findings of Dr. Segal's first study:
Personality traits do not appear to be influenced by the way people are
treated because of appearance.
Typical personality correlations for identical twins are .5. Here are the combined results from both studies of Unrelated Look-Alikes, reported in Segal, Graham, and Ettinger (Personality and Individual Differences, 2013):