A basic hypothesis is that cultural evolutionary processes sustain differences between groups, these differences have evolutionary relevance and they would not otherwise occur in a system without cultural transmission. The empirical challenge is that groups vary for many reasons, and isolating the causal effects of culture often requires appropriate data and a quasi-experimental approach to analysis. We address this challenge with historical data from the final Soviet census of 1989, and our analysis is an example of the epidemiological approach to identifying cultural variation. We find that the fertility decisions of Armenian, Georgian and Azeri parents living in Soviet-era Russia were significantly more son-biased than those of other ethnic groups in Russia. This bias for sons took the form of differential stopping rules; families with sons stopped having children sooner than families without sons. This finding suggests that the increase in sex ratios at birth in the Caucasus, which began in the 1990s, reflects a cultural preference for sons that predates the end of the Soviet Union. This result also supports one of the key hypotheses of gene–culture coevolution, namely that cultural evolutionary processes can support group-level differences in selection pressures that would not otherwise occur in a system without culture.

While previous studies have confirmed the negative effects of son preference on the prenatal care received by girls, few have examined its effect on birth outcomes. This study contributes to the literature on son preference by examining this relationship. The degree of son preference is measured by the sex ratio at birth, and the data were obtained from the birth registry of South Korea, which has a long history of strong son preference. We find that girls are more likely to be born with low birth weight when son preference is stronger. In addition, when son preference is stronger, girls are more likely to be born outside hospitals, which implies that mothers conceiving girls make fewer prenatal visits to the hospital when their son preference is stronger.

This paper investigates the relationship between women’s education and desire for additional children across the six economic regions of Vietnam. The study employed data from the nationally representative Vietnam Multiple Indicator Cluster Survey (MICS) 2014. Probit regression results showed that for women with one child, higher levels of education were associated with higher fertility desire in two out of six regions. Similar results were found for women with two or more children. Children’s sex composition played a role in the desire for additional children, reflecting both son preference and mixed-gender preference. In Vietnam overall, among women with at least one boy, those with lower levels of education were more likely not to want another child. The results, however, differed by region. The findings suggest that the social and economic context of each region, particularly sex ratio at birth and total fertility rate, should be taken into account when designing population policies in Vietnam.

India's sex ratio at birth (SRB) has become increasingly masculine, coinciding with a declining total fertility rate. Couples often resort to sex-selective abortion or even infanticide to ensure the birth of a son. We use household-level data from all four waves of India's National Family Health Survey (NFHS) to investigate the effect of India's demographic transition on the SRB. Mixed-effects logit regression analysis demonstrates that since the early 1990s, the probability of a third-order birth being male is decreasing in the number of sons previously born, while for second-order births, this effect does not become apparent until the 2000s. Accounting for geographic heterogeneity in the fertility transition, we find additional heterogeneity in son preference and sex selection at the village/neighborhood level. This heterogeneity has strengthened over time at both second- and third-order births and in more and less gender skewed regions of the country, suggesting potential convergence in sex ratios across India. By incorporating the most recent 2015–16 round of the NFHS, we demonstrate that previously documented trends in sex selection continue, and additionally that sex selection is increasingly occurring at lower parities as the desire for a smaller family combines with the traditional preference for sons.

This article examines the parent–child relations within rural-to-urban migrant households to explore the continuations and changes in the patrilineal family system under the forces of migration and urbanization in late-socialist China. Based on ethnographic data collected between 2008 and 2015 in Shanghai, it takes a processual approach to understand son preference as a contextualized family practice and examines four aspects of parent–child relations in migrant households: reproductive strategy, childrearing practices, educational investment, and parental expectation of adult children. Through exploring intimate negotiations between migrant parents and their children over material and emotional resources at different life stages, this article demonstrates how the gendered parent–child relations in migrant households in Shanghai have been shifting away from the traditional focus on sons and gradually giving way to pragmatic adjustments and emotional redefinition under the forces of socialist institutions and capitalist markets.

Drawing from ethnographic data from 48 households in four villages in rural Anhui, this study explores how two practices known for upholding son preference are affected by rural–urban out-migration, with a particular focus on the division of labour in agricultural work and patrilocality. The study deploys the concepts of an intergenerational contract and the “unsubstitutability” of sons and finds that a weakening of the intergenerational contract can take place without substantially challenging the unsubstitutability of sons. The study concludes that although male out-migration undermines the argument that sons are needed to secure male manual labour in family farming, the vital role of male labour as a rural livelihood strategy largely persists. Moreover, although the study identifies migration-induced exceptions, patrilocality remains the main organizing principle for social and economic life for both male and female migrants. Hence, the study finds little support for the prospect that migration is attenuating son preference in rural China.

The media and generalist scholarly work have created a conventional wisdom that China's one-child policy is the driver of the country's skewed sex ratio and so should be relaxed in order to ameliorate the imbalance. However, we show through historical, domestic and international comparisons that son preference, which we treat as an observable and measurable variable made up of labour, ritual, inheritance and old-age security practices and policies, is crucial to explaining the imbalanced sex ratio at birth. China's sex ratio cannot fully normalize without addressing son preference.