Bagi Ilmu

"We were going to the same church, and there were people who were very interested to have the two of us date," says Young, 32, of Cincinnati. "They'd say, 'You would look really good together and would have cute kids' — before we were dating."

Everybody knows romantic partners who look as if they belong together. But just why people are sometimes drawn to look-alikes isn't necessarily coincidence. It's fodder for research that spans subjects from evolution to psychology to attraction and mating preferences, to try to explain why some people may unconsciously seek out partners with similar features.

"When you have a face that looks more like you, you tend to trust it more and think it looks more cooperative," says Tony Little, a research fellow in psychology at the University of Stirling in Scotland. He is among a small group of researchers studying the role of the human face in mating choices.

Research by psychologist R. Chris Fraley of the University of Illinois in Urbana-Champaign used digitally morphed photos of a subject's face and a stranger's face; he found that morphed faces were more attractive to subjects when their own face was included. The experiment was part of a study he co-wrote in 2010 in the Personality and Social Psychology Bulletin.

"I do think there's an innate tendency for people, myself included, to be attracted to people who look like them. There's a familiarness to it," says Sharon Young, a college administrator.

A new dating website called Find Your FaceMate even uses facial-recognition software to suggest pairings. The official launch is July 10, says founder Christina Bloom of New York. But although facial attraction may ignite a relationship, it takes more to keep it going, she says.

Jessie King, 26, of St. Augustine, Fla., says she and boyfriend Jeff Cagle, 32, are both blond.

"People like to see similars together," says King, a health educator. "We get comments like: 'You guys are cute together. You look like a good couple.' "

Redheads Heather and Tony Capraro, 41 and 49, of Concord, N.H., both were married before, but not to look-alikes. "When we're out, people think we're brother and sister," he says.

Jim Rock, 41, a lawyer from Holladay, Utah, says his wife, Grace Rock, 36, "has six siblings but looks more like me than them."

Debra Lieberman, an evolutionary psychologist at the University of Miami in Coral Gables, Fla., says Freud was wrong about people being unconsciously attracted to their opposite-sex parent; humans have evolved sophisticated inbreeding avoidance systems and develop strong aversions toward those seen as a close genetic relative.

She believes it's more about "the similarity someone else has to the template that I built up of what counts as a healthy male. It might come from what my father looks like and any other males I was around quite frequently growing up."

James and Katrina Vong, 31 and 32, are federal employees stationed in Yokosuka, Japan. He's Cambodian and she's Filipino, but "sometimes we get weird looks when we hold hands because our resemblance seems more like siblings," he says.

Bull and Ackerman, 33 and 32, of Evanston, Ill., met in college; they noticed their resemblance but dated others, too. "Before Allison," he says, "I dated somebody 4-foot-11 and brunette."