Ever wondered what your exes have in common, and how they differ from people you never dated?

The people one dates share many similarities -- both physically and personality-wise -- a new University of California study has found.

For observable qualities like attractiveness, similarity emerges because attractive people seduce other attractive people. But, researchers said, for qualities that vary greatly depending on where you live (like education or religion) similarity emerges because educated or religious people tend to meet each other, not because educated or religious people actively select each other.

"Do people have a type? Yes," said the study's primary author, Paul Eastwick, associate professor of psychology. "But sometimes it reflects your personal desirability and sometimes it reflects where you live."

The study was published online this month in the Journal of Personality and Social Psychology of the American Psychological Association.

The article, which comprises three slightly different studies, looked at the characteristics of people in more than 1,000 past and present heterosexual relationships. The information was provided voluntarily through social media sites and live interviews in recent years, culminating in 2014.

In one of the studies, researchers found that people's past partners have similar physical qualities. This was true even when the partners were short-term or casual relationships. ." ..during the partner selection process, people may have difficulty differentiating between partners that prove to be casual and short-term versus committed and long-term," the study said.

While intelligence or educational level also played a role, Eastwick said, it was often related to where the people went to school or the field in which they worked.

"A second study examined the ex-partners of several hundred young adults sampled from schools across the United States. The exes of a particular person tended to be very similar on variables like education, religiosity, and intelligence, but this type of similarity was entirely due to the school that people attended. Within their local school context, people were no more or less likely to select educated, intelligent, or religious partners."

The study differs from most other research on relationships because this study surveys people's relationships over time, not just one committed relationship, Eastwick said.