From the days of "Romeo and Juliet," literature, art and the movies have long found inspiration in the conflicts between parents and their offspring over whom the young people should marry.

From the days of "Romeo and Juliet," literature, art and the movies have long found inspiration in the conflicts between parents and their offspring over whom the young people should marry.

Just in time for spring weddings, scientists decided to put what has become an entertainment cliche to an empirical test. Do young people and their parents really disagree about the qualities of a suitable mate?

In a study involving American, Dutch and Kurdish students, psychologists in the Netherlands found that the cliche is, in fact, true.

Young Americans told the researchers that qualities they would find unappealing in a potential mate included low intelligence and physical unattractiveness. But they said their parents would object to a mate who was of a different ethnicity, was poor or lacked a good family background.

The responses of Dutch and Kurdish students were similar in that young people invariably considered the potential mate's attractiveness the most important quality, whereas parents uniformly paid more attention to the suitors' social background or group affiliation — race, religious background and social class.

Shakespeare and Hollywood can duke it out about whether the young people or their parents are right, but the interesting question from a scientific perspective is why this conflict occurs at all.

Abraham P. Buunk, Justin H. Park and Shelli L. Dubbs at the University of Groningen, who published their findings in the Review of General Psychology, said the consistency of the conflict across cultures suggests the hand of evolution: Parents and offspring clash, the researchers argued, because their genetic self-interests, while overlapping, are not identical.

The reason young people care so much about intellectual and physical attractiveness, the scientists suggested, is that these characteristics are markers of genetic fitness. By contrast, they said, parents care about group affiliations because parents are primarily interested in whether an incoming member of the family is likely to make a good parent — and a good all-around team player.

"When it comes to mating, the key is that the kinds of mates who score high on 'good genes' traits" — such as attractiveness, sense of humor — "tend to score low on 'good parent' traits, and vice versa," said Park, a social psychologist who studies relationships.

Historian Stephanie Coontz argues that the researchers did not draw a clear enough distinction between love and marriage. Evolution might play a big role in shaping the reproductive drive, she says, but it would be a mistake to think that the institution of marriage has primarily been about either love or reproduction.

Nearly everyone in the West — and growing numbers of young people elsewhere in the world — believes in the ideal of marrying for love, an idea that would have been ludicrous and dangerous a century ago, said Coontz, author of "Marriage, a History: How Love Conquered Marriage."

Coontz traces the change in attitudes about marriage to the fact that growing economic self-reliance has made it less likely that people need to marry for money.