How Does Religion Influence Decisions About Marriage and Family?

This post has been unlocked through a generous grant from the Lilly Endowment for the Association of Religion Data Archives (ARDA). The graphs you see here use data that is publicly available for download and analysis through link(s) provided in the text below.

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As social scientists we are not just concerned with whether someone identifies with a religious tradition, although that is certainly important. We are also interested in whether that religion has a measurable impact on the way that they go about their daily lives. Does it change the way they make decisions? Does it generate a different set of values? Does religious faith lead to a different worldview? Religious beliefs are certainly important, but seeing how that mental framework shapes actual behavior in a random sample of the population is crucial in the world of social science. 

One area in which religiosity is highly likely to have a measurable impact is marriage and family. Every major religious tradition has centuries of theology and instruction about the value of finding a spouse and one common thread that runs through religious traditions is the admonition to have children. There is, of course, a very logistical reason for this - it’s much easier for a religious group to perpetuate itself through generational transfer of religious traditions and belief. But many faith traditions speak of how children are a gift and having offspring is part of the natural order that was created by God. 

However, do those encouragements by faith leaders actually lead to real changes in behavior among those religious adherents? The Association of Religion Data Archives (ARDA) hosts a dataset that is incredibly helpful in this regard. It’s called The National Survey of Family Growth (NSFG), and the combined size of the dataset is over 10,000 respondents who were between the ages of 15 and 50 when they took part in the research. It was funded by the Center for Disease Control’s National Center for Health Statistics. It asks hundreds of questions of individuals related to topics about marriage and family.  It also includes a question about the religious tradition of the respondent. 

Let’s start by taking a look at a question about the current marital status of the respondent. 

A significant portion of this sample is currently married. In many faith traditions, it’s about half of respondents including evangelicals, mainline Protestants, and those of other faith groups like Muslims, Buddhists, and Latter-day Saints. There were two traditions who were clear outliers here - just 21% of Black Protestants were currently married and it was ten points higher for those with no religious affiliation (31%). The corollary to that is the share of the sample who had never been married. The only group where a majority hadn’t walked down the aisle were Black Protestants at 56%, while 46% of nones had never been married. The group that was the least likely to never be married were evangelicals at just 31%. 

When it comes to the other two options - cohabitating with a partner without being married and being divorced/separated, there isn’t a lot of variation. It is noteworthy that across all four Christian categories (evangelical, mainline, Black Protestant, and Catholic) that there was no statistically significant difference in cohabitation rates - they were all between 11% and 13% of the sample. The same is largely true when it comes to divorce and separation. An evangelical was just as likely as a Catholic to select one of these two options. 

One interesting extension of this previous bit of analysis is to look at the sexual activity of people who have never been married in the sample by religious tradition. One of the most important aspects of evangelicalism over the last several decades is “purity culture.” This is a worldview that teaches adherents to abstain from sexual behavior before they get married. To try to understand if evangelicals’ behavior was impacted by this belief system, I restricted the sample to just those who had never been married and were at least 25 years old and then analyzed how many sexual partners they reported in the prior year. 

About 36% of evangelicals reported having no sexual partners in the prior year. That was statistically the same as mainline Protestants and largely in line with those from non-Christian faith groups. That share was about ten points higher than the share of Catholics and the nones who reported zero sexual partners in the prior year. There is some evidence that purity culture does have a measurable impact on actual behavior, but it’s still important to point out that nearly two-thirds of unmarried evangelicals had sex in the prior year. So, it’s certainly not the dominant posture when it comes to sexual behavior. 

The most likely response option was one of monogamy. Nearly half the unmarried sample claimed one sexual partner in the prior year. Think of it this way - here’s the share of people in each group that indicated that they had no more than one sexual partner in the prior year: 

• Evangelicals - 77%

• Mainline - 82%

• Black Protestant - 72%

• Catholic - 75%

• Other Religion - 75%

• No Religion - 79%

To say that there’s a great deal of sexual promiscuity in the population finds little empirical support from this data. About three quarters of unmarried 15-50 year olds have had zero or one sexual partner in the prior twelve months. Additionally, the share who have had at least three partners is vanishingly small - just 7% of the unmarried sample. 

Of course, the natural extension of this conversation about marital status and sexual partners is fertility. In the part of the questionnaire that was focused on just the female respondents, they were asked how many times that they had been pregnant in their life. I broke the sample down into Protestant, Catholic, those from non-Christian traditions, and those who claimed no religious affiliation. The graph above is the share who reported never being pregnant and I calculated this for the entire age range of the sample from 15 to 50 years old. 

Among the youngest women in the sample, there are only small differences in the share who have never had been pregnant. It does look like those from non-Christian faiths are slightly more likely to have not gotten pregnant, though. But when looking at women in the sample who are at least thirty years old, there does appear to be some distinct differences in the share who have never been pregnant. For instance, among those who are 35 years old about 13% of Protestant women hadn’t been pregnant, it was double that rate among non-religious women - about 25%. And those gaps persist throughout the rest of the data - non-religious women are about twice as likely to never have gotten pregnant compared to those of any faith tradition. 

That difference also emerges when looking at a question that asks, “total number of babies that have been born alive.” I just looked at women in the sample who were between the ages of 35 and 50 with the assumption that this is when most would have had all the children they were going to give birth to in their lives. 

For Protestant women, the most likely response option was two children. In fact, that’s also the most popular choice for Catholic women and those from other non-Christian traditions, too. At least a third of all women in those three groups had given birth to two babies. The next most likely choice for those groups was having three kids. That was the case for about a quarter of the sample of Protestants, Catholics, and the ‘other religion’ group. One common conception about Roman Catholics is that they have larger families due to their adherence to church teachings regarding contraception. But, there’s really no support for that belief in this data. About a third of Protestant women had at least three children, it was nearly the same percentage among Catholics (35%). The group that clearly has the biggest family is those from non-Christian groups - 43% of them have at least three children and they are almost twice as likely to have at least four kids compared to Catholics. 

The distribution of responses for non-religious women clearly diverges from the other three categories that I created. The most likely response option for non-religious women between the ages of 35 and 50 was that they have had zero children - 28% chose this option. Another 25% reported that they had given birth once. Among the nones, 53% of women had zero or one child. It was 31% of Protestants, 30% Catholics, and 25% of non-Christians. Just 23% of non-religious women had three or more children, that’s also at least ten points lower than the other groups. The conclusion here is clear - non-religious women have lower fertility than those of any other faith tradition. 

But is that due to some factor that is external to religion? Maybe it’s because the educational attainment of the nones is different from the religious sample. Or they may have a different level of income. There’s also the possibility that this could be explained by the fact that religious people tend to marry at higher rates than the non-religious, as we have previously seen. To test this, I put together a regression model that controlled for those factors (along with race). I estimated the number of children per woman among the religious and non-religious sample. 

Among women in their teens and early twenties, the number of children born does not significantly differ between the two groups. However, when one looks at women in their late twenties and onward, it’s clear that the religious group has a higher fertility rate than the non-religious. A thirty year old non-religious woman has, on average, one child. For a religious woman of the same age it's about 1.25 kids. The gap among forty year olds is slightly higher - about one third of a child. Among the oldest women in the sample the gap is even larger with a woman in her late forties having about 2.3 children while a non-religious woman has about 1.85. 

Given that the previous regression controls for a number of factors that could lead to a difference in fertility like education, income, race, and age, it’s hard to not conclude that religious affiliation has a demonstrable impact on life choices like how many children to have. There have been a number of stories written about the growth in the pro-natalist movement in the last decade. And Elon Musk has certainly talked about it at length just this year. When having these discussions it’s important to recognize that a number of factors can make one more (or less) likely to have children. From this analysis, it’s readily apparent that the decline of religion is somewhat to blame for the decline in American fertility. 

Code for this post can be found here.