Large families in the United States are more likely to hold culturally conservative attitudes and this differential fertility can help sustain large pockets of opposition to change, according to new research published in Proceedings of the National Academy of Sciences.
“For the past several years, I have been studying how fertility variation within one generation reshapes the next. I started by looking at outcomes that are common terrain for economists, like education. But sooner or later, I took interest in cultural traits as outcomes, especially those connected with ideas about how the family should look,” said study author Tom Vogl, an associate professor at the University of California San Diego.
The researchers analyzed data provided by 12,017 participants between 2004 and 2018 during the General Social Survey, a nationally representative survey of U.S. adults. The survey collected data about family size and also asked participants about their views regarding abortion and same-sex marriage.
The researchers found a link between family size and conservative values. People with a greater number of siblings tended to be more opposed to abortion and same-sex marriage, which was mostly explained by greater religiosity and lower educational attainment.
“Natural selection is a silent warrior in America’s culture wars,” the researchers wrote in their study.
The association between the number of siblings and attitudes was responsible for increasing opposition to abortion from 53% to 57%. Similarly, the association between the number of siblings and attitudes was responsible for increasing opposition to same-sex marriage from 38% to 41%.
The results indicate “that slow-moving demographic processes can influence culture,” Vogl told PsyPost.
“People with conservative attitudes about how the family should look tend to have larger families (more children, more siblings), which makes these attitudes — like opposition to abortion and gay marriage — more prevalent across generations. New ideas can spread rapidly within a generation, as they have for gay marriage over the past two decades, but demographic forces push back against them.”
“Our research does not establish why traditional-family conservatism is related to family size. Our preferred theory is that many facets of traditional-family conservatism — opposition to abortion, homosexuality, and women’s work, for example — are inherently pronatalist, so the concentration of these attitudes in larger families makes sense,” Vogl explained.
“But beyond showing that the family size associations are specific to traditional-family conservatism and do not extend to other forms of conservatism, we do not shed light on the mechanism. That would be a useful direction for future research.”
“Despite the importance of so-called ‘family values’ issues in U.S. politics, the demographic phenomenon we document does not have immediate partisan implications. Family size does not have a robust relationship with partisan affiliation,” Vogl added.
The study, “Differential fertility makes society more conservative on family values“, was authored by Tom S. Vogl and Jeremy Freese.