We may think that we are all very different, but new research suggests that everyone falls into four clusters of personality types.
Apparently we are either average, reserved, self-centered or a role model, The sun reports.
Experts from Northwestern University asked 1.5 million people around the world to formulate their findings.
The four clusters are scored in proportion to the different proportions of the "big five" personality traits.
These characterize people through their openness, conscientiousness, extraversion, acceptability and neuroticism.
According to the team behind the study, the results challenge all existing ideas in psychology.
"People have tried to classify personality types since the time of Hippocrates, but previous scientific literature has discovered that this is nonsense," said co-author William Revelle.
"Now these data show that there are higher densities of certain personality types."
The concept of personality types remains controversial in psychology, with difficult scientific evidence difficult to find.
Previous attempts based on small research groups created results that often could not be replicated in larger studies.
But this research was different, combining a computational approach with data from four questionnaires with more than 1.5 million respondents from around the world.
The questionnaires had between 44 and 300 questions and people volunteered online as a way to learn more about their own personality.
Study leader Luís Amaral – professor of chemical and biological engineering – says: "Personality types existed only in self-help literature and had no place in scientific journals.
"Now we think that this will change because of this study.
"An investigation with a dataset that was so large would not have been possible before the web.
"Earlier, researchers would recruit undergrads on campus and maybe get a few hundred people.
"Now we have all these online resources available and data is shared."
So, what do you think you are?
This article originally appeared on The Sun and is being republished with permission.