Ever wonder why we're attracted to some people and not to others? Here's a rundown of the latest research on the rules of attraction:

  • First: We like symmetry. Scientists at the University of New Mexico asked volunteers to rate the attractiveness of people in a set of photos. Then, they altered the pictures so the faces were slightly less symmetrical. And even though the changes weren't visible on a conscious level, the scores on the altered pictures went down.
  • Another fact about attraction: Opposites DON'T attract. Psychologist Dr. Eva Klohnen says we're drawn to people with similar attitudes and values. But research also shows that couples who are physically similar have happier marriages.
  • Also, both men and women find humor attractive, but in different ways. Psychologist Dr. Eric Bressler says that women are attracted to men who make them laugh, but men prefer women who appreciate their humor and laugh at their jokes.
  • And the last rule of attraction can be a deal-breaker: The first kiss. Relationship expert Dr. Laura Berman says that two-thirds of people will end a relationship after a bad first kiss. That's because kissing is an important way for couples to bond and remain close. In fact, Dr. Berman says that couples who share at least one 10-second kiss a day report being happier and less stressed than couples who don't.