How Religious Beliefs about a Couple’s Compatibility Lead to Better Outcomes

They were using Tu Vi, an ancient belief system in Vietnam with Taoist roots stretching back to at least 16th century China. Tu Vi offers individuals and couples predictions about future events—such as marriages, births, deaths, business prospects, and travels. These are based on a person’s time of birth and lunar birth year in the 12-year zodiac cycle.

Tu Vi’s popularity in Vietnam has ebbed and flowed in the 20th century, and it regained widespread popularity in the past 30 years. But little is known about whether these sorts of religious belief systems, which are independent of any institutions or doctrine, affect people’s behavior.

In particular, Nguyen wondered how much these beliefs really matter to couples when it comes to making marriage decisions. She also wondered: What are the implications for their marriages if they do have what Tu Vi considers an auspicious match?

To explore these questions, Nguyen collaborated with Edoardo Ciscato, at KU Leuven, and Quoc-Anh Do, at Monash University. They found that Tu Vi is a pervasive and important part of Vietnamese life.

More so, they also found that couples in what are deemed auspicious marriages benefit in measurable ways: they earn more and have a higher standard of living, for example, and their children are less likely to drop out of school.

Which is not to say that the stars were right in their predictions. Nguyen says that there’s a self-fulfilling prophecy at work: when a couple’s social circle believes a marriage is auspicious, they are more likely to step in and offer help, buoying the couple through hard times.

“Auspicious couples indeed end up doing better, and this belief is passed down through generations,” Nguyen says.

Assessing how much Tu Vi matters

The researchers collaborated with a think tank to conduct a survey of ethnic Vietnamese people in 2020. The results highlighted how prevalent Tu Vi is: eighty-two percent knew about the system and how to get information on detailed predictions; 45 percent believed that their family and relatives care about Tu Vi; and 31 percent considered Tu Vi to some extent in their own marriage.

To understand how much these beliefs in marital fortune influence marriage formation, the researchers turned to census data, as well as data from the Vietnamese Population Survey, focusing specifically on four regions of the country, two urban and two rural. From the 2009 census, they analyzed a sample of 916,314 married couples. Women in this sample ranged in age from 19 to 33 years old, while men ranged in age from 21 to 35. Researchers also analyzed similar, but smaller, datasets on couples in the 1989 and 1999 censuses, as well as Population Survey data from 2006–2018. In all, the different samples include 1.36 million couples.

Using information about when each spouse was born, the researchers were able to see how auspicious every match was considered. They found that 34 percent of the matches were auspicious (about one-half percent higher than you would expect from random matching), 53 percent were neutral, and 14 percent were inauspicious (about 3 percent lower than random matching).

Overall, the researchers found that Tu Vi matters to the formation of marriages, and in fact was about 6 to 7 percent as important to marriage-matching as a couple’s education and age. Auspicious marriages were more common in provinces where religious observance is higher and social ties are stronger, and they occurred less frequently in richer areas. But no matter how many variables the researchers considered, they still found evidence of auspiciousness.

“When we try to account for a lot of other things, like education, age, or the region you live in, auspiciousness still enters into consideration,” Nguyen says.

What is the impact of an auspicious marriage?

The researchers next wanted to understand if couples in auspicious marriages were better off than those in non-auspicious matches.

To their surprise, the answer appeared to be yes. The survey data showed that those in auspicious marriages earn 2.2 percent more and have household expenditures that are 2.7 percent higher than others in their socioeconomic and educational class. They also have better self-reported living standards, and their children are less likely to fall behind in school.

What drives this good fortune? Nguyen attributes it to greater support from an auspicious couple’s friends and family, especially in difficult times. On the other hand, friends and family may see inauspicious couples as likely to fail anyway and thus not worth the extra help.

Indeed, auspicious couples enjoyed 9 percent more support on average than couples who don’t follow Tu Vi beliefs, according to the survey data. Auspicious couples who were poor were 18 percent more likely to receive such support, while auspicious couples dealing with the hospitalization of a family member received 24 percent more support. Such couples also are less likely to be forced to liquidate their assets or to take out loans from formal institutions (as opposed to friends and family).

Like other values and norms, belief in marriage auspiciousness has persisted because it’s passed down through generations and reinforced through community, says Nguyen.

“Even if the couple themselves do not strongly believe in this but think that their family and friends strongly believe in this, there’s an incentive for them to match auspiciously—if getting help from family and friends when you’re going through hardship is important,” she says.

Having examined the impact of Tu Vi on marriages, Nguyen and her colleagues plan to next study the impact of auspicious beliefs on business relationships. As Tu Vi becomes more popular, the researchers are noticing a growing number of advertisements by small-business owners seeking partners or employees who are an auspicious match.

“It’s definitely something going on,” Nguyen says, “but how big or how important it is, we don’t know yet.”