Effects of Sex, Race, Ethnicity and Marital Status on the Relationship between Intelligence and Fertility

Sep 18, 2026

Uploaded by Mason

Examines how sex, race, ethnicity, and marital status relate to the connection between intelligence and fertility in the United States. Using NLSY79 data, results are analyzed separately for Blacks, non-Hispanic Whites, and Hispanics, emphasizing differential fertility pathways. Key findings indicate fertility-reducing effects of intelligence differ across groups, are stronger for females and unmarried individuals, and are largely mediated by education for married women. The text also reviews prior evidence across demographic transitions and decades.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages42

Reading Time1 h 46 min

AccessFree to download

Key Findings

Mechanisms by Group, Sex, and Marital Status

Background and Prior Evidence

151 Effects of Sex, Race, Ethnicity and Marital Status on the Relationship between Intelligence and Fertility * Gerhard Meisenberg Anubhav Kaul Ross University School of Medicine, Portsmouth, Dominica A negative relationship between intelligence and fertility in the United States has been described repeatedly, but little is known about the mechanisms that are responsible for this effect. Using data from the NLSY79, we investigate this issue separately for Blacks, non-Hispanic Whites and Hispanics. The major findings are: (1) Differential fertility would reduce the average IQ of the American population by up to 1.2 points per generation in the absence of migration and environmental changes; (2) About 0.4 points of the effect is caused by selection within racial and ethnic groups, and therest is caused by between-group selection; (3) Differential fertility by intelligence is greatest in Hispanics and smallest in non-Hispanic Whites; (4) The fertility-reducing effect of intelligence is greater in females than males; (5) The IQfertility relationship is far stronger for unmarried than married people, especially females; (5) High intelligence does not reduce the desire for children; (6) High intelligence does not reduce the likelihood of marriage; (7) Education is the principal mediator of the IQ effect for married women. Key Words: Intelligence; NLSY; Education; Fertility; Ethnicity; Race; Marriage; Dysgenics. Children tend to be similar to their parents, both through cultural transmission in families and genetic inheritance. This similarity extends to personality traits and cognitive abilities that are important for people’s functioning in society and that determine the “culture” of a nation or group. Therefore differential fertility influences long-term cultural trends on time scales ranging from one generation to many millennia, and the major rationale for the study of differential fertility is the prediction of longterm cultural trends. There is substantial evidence that before the industrial * [Corresponding author: Gmeisenberg@rossmed.edu.dm](Corresponding author: Gmeisenberg@rossmed.edu.dm)[ ](Corresponding author: Gmeisenberg@rossmed.edu.dm)Volume L Number 3, Spring 2010 152 Gerhard Meisenberg and Anubhav Kaul revolution, the wealthier and socially successful sections of society had the highest reproductive rates. This has been demonstrated for preindustrial Europe (Clark & Hamilton, 2006; Hadeishi, 2003; Pettay et al. , 2007; Stys, 1957/58), East Asia (Harrell, 1985; Lamson, 1935; Notestein, 1938), and diverse anthropological populations (Borgerhoff Mulder, 1987; Chagnon, 1980; Irons, 1980) . The massive cultural and economic advances from the Middle Age toward the Industrial Revolution has been attributed to strong differential fertility favoring the wealthier classes in pre-industrial England (Clark, 2007) . However, since the early years of the 20th century, a negative relationship of fertility with social class has been a regular finding both in Britain (Notestein, 1936; Stevenson, 1920) and the United States (Kiser, 1932) . These early observations were followed by studies showing that throughout the first half of the 20th century fertility was negatively related not only to measures of social class, but also to measures of intelligence (Anastasi, 1956; Cattell, 1936, 1937; Dawson, 1932/33), although atypical results were obtained occasionally (Willoughby & Coogan, 1940) . The baby boom years of the 1960s produced some studies reporting a negligible or even slightly positive relationship between intelligence and fertility in mainly white middle-class American samples (Bajema, 1963, 1968; Falek, 1971; Higgins et al. , 1962; Waller, 1971) . Even the subfertility of men in Who’s Who in America seemed to disappear for cohorts born after 1910 (Kirk, 1957) . The conclusion at the time was that dysgenic fertility had been a transient phenomenon of the demographic transition, when contraceptive h

FAQs

What dataset does the study use to investigate intelligence and fertility?

It uses data from the NLSY79 to analyze relationships separately for Blacks, non-Hispanic Whites, and Hispanics.

How does intelligence relate to fertility differently across sex and marital status?

The fertility-reducing effect of intelligence is greater in females than males, and the IQ-fertility relationship is far stronger for unmarried than married people, especially females.

What explains the intelligence effect for married women in the study’s findings?

Education is identified as the principal mediator of the IQ effect for married women.

Sep 18, 2026

Uploaded by Mason