Shared moral values are less important than compatible personalities as a recipe for a good marriage, according to a study released on Sunday.

Married couples often share the same attitudes about faith and other values, researchers from the University of Iowa found. But those with personalities similar to their spouses were the happiest.

“People may be attracted to those who have similar attitudes, values and beliefs and even marry them,” the researchers said, and those qualities are easy to spot in a potential mate. Attitudes toward subjects such as religion or politics “are highly visible,” they said.

But how married people behave was shown to have a greater effect on happiness.

“Being in a committed relationship entails regular interaction and requires extensive coordination in dealing with tasks, issues and problems of daily living,” the study found. Differences in how to deal with everyday matters can lead to “more friction and conflict,” it said.

Personality-driven traits - like being open, easy-going or organized - are likely to play a bigger role in the marriage, the researchers found after studying 291 newly married couples.

The newlyweds were married for an average of five months when the data was collected late in 2000 and had dated for an average of 3-1/2 years.

The couples were participants in the Iowa Marital Assessment Project, a long-term study being conducted by the university with funding from the National Institute of Mental Health under the National Institutes of Health.

Participants were asked to evaluate their own traits and were videotaped interacting with each other.

Partners who rated their marriages as highly satisfactory were found to have more common personalities.

Similar attitudes among the couples, however, showed no clear impact on happiness, according to the study published in the American Psychological Association’s Journal of Personality and Social Psychology.