Sons of War: How Ethnic Violence Strengthened Son Preference

Armenia and Azerbaijan share two striking demographic features: a strong preference for sons and a widespread use of abortion. They also share a long and violent history of conflict over the Nagorno-Karabakh enclave. 

In our research, we ask a simple but unsettling question: did this conflict change how families think about having children, and in particular, whether to have a boy or a girl? War does more than destroy lives and infrastructure. It reshapes identities, heightens insecurity, and alters expectations about the future. In this context, we explore whether recurring violence, displacement, and ethnic tension contributed to the unusually high sex ratios at birth observed in both countries since the late 1980s. As violent conflicts re-emerge across the globe, examining how they shape family decisions becomes essential.

Conflict and Family Decisions

Families in Armenia and Azerbaijan show a clear preference for sons, a preference reflected in some of the highest sex ratios at birth in the world. The sex ratio at birth (SRB) measures how many boys are born for every 100 girls. Under natural conditions, without sex selection, this number is around 105, as male fetuses have a higher likelihood of surviving the pregnancy and be carried to term. Starting in the late 1980s, both countries began recording alarmingly high sex ratios at birth, with levels peaking in the early 2000s. These patterns cannot be explained by biology alone. Instead, they point to the growing use of sex selection. Families have relied on sex-selective abortion, made possible by access to ultrasound technology, as well as “stopping rules”, continuing to have children until the desired number of sons is reached. Together, these practices have reshaped birth patterns in profound and lasting ways. 

For decades, Armenia and Azerbaijan have clashed over Nagorno-Karabakh, a predominantly Armenian region within Azerbaijan. The conflict, rooted in Soviet-era borders, erupted into the First Nagorno-Karabakh War (1988–1994), which ended with the region emerging as a de facto independent Armenian-backed territory. However, the conflict remained unresolved, flaring again in 2016 and more dramatically in 2020, when a six-week war allowed Azerbaijan to regain significant territory. In 2023, Azerbaijan’s offensive ended the self-proclaimed Republic of Artsakh, and in 2025 a peace declaration ended decades of fighting, which caused over 30,000 deaths and displaced more than a million people.

The Methodology

To explore how conflict shapes fertility decisions, we combine household survey data with detailed records of conflict-related casualties. Our focus is on a striking question: do families respond to violence by trying to have boys, the “sons of war”? Are pregnant women more likely to turn to sex-selective abortion when the future feels uncertain or dangerous?

We tackle this by comparing families exposed to different levels of conflict across regions and over time, allowing us to see how violence influences reproductive choices. To measure son preference, we examine the gender of children born after conflict exposure, paying special attention to families who haven’t yet had a son. By comparing  families that have only daughters to those who have only sons, we can see whether war intensifies the desire for male children. If it does, we would expect families without sons to be the ones most likely to give birth to a son, indicating that they are resorting to sex selection. 

What We Find: Exposure to Ethnic Violence Increases Preference for Sons

Our results reveal a striking pattern: families exposed to conflict are more likely to have children in the year following violence — and this effect is almost entirely driven by families without sons. In fact, increases in violence raise the probability of giving birth by about 12%, and for son-less families, this surge comes almost entirely from male births. In contrast, families with at least one son and one daughter show no significant change. This suggests that families without sons deliberately continue having children after conflict and increasingly rely on sex selection to ensure a boy.

While researching the Nagorno-Karabakh conflict, we noticed discrepancies between standard conflict datasets and historians’ casualty estimates. To investigate this further, we searched for alternative sources of conflict casualties and obtained a memoir of Armenian soldiers and volunteers who fought in the Nagorno-Karabakh conflict, compiled by the Armenian government. We used this memoir to construct a more accurate death toll. Repeating our analysis with this independent measure of conflict exposure produced the same results, confirming the robustness of our findings.

What Could Explain These Patterns?

We believe two forces may help explain the increase in male births that we observe. The first is replacement. War brings loss, and for families who lose children the desire to “replace” lost children can be a driver in the increase in births that we observe. The second mechanism is more collective. Ethnic conflict often strengthens feelings of group identity and vulnerability. In moments when communities feel under threat, private decisions can take on broader meaning. Bearing children, especially sons, may be seen not only as a family matter but as a way of contributing to the group’s survival and future. In this sense, fertility becomes a tool that each individual has to strengthen their group identity. 

To investigate the replacement mechanism, we turned our attention to the women who suffered the loss of a child. Their choices reveal a striking pattern of replacement behavior. Women who lost a child during the conflict are more likely to have another, but this effect is driven almost entirely by the likelihood of having a son. The gender of the lost child makes the pattern even clearer: losing a son raises the probability of having another son by 12%, while the chance of having a daughter declines correspondingly. In other words, families actively “replace” lost sons. By contrast, women who lost a daughter also tend to have another child, but there is no evidence that they manipulate the child’s sex. This shows how deeply son preference can shape reproductive decisions, even in the wake of profound personal loss. 

Why This Matters

Most research on conflict focuses on mortality, displacement, or economic destruction. But conflict also shapes social norms and family decisions in profound ways. Our findings suggest that ethnic conflict does not merely disrupt demographic patterns but that it can also reinforce and intensify existing gender biases. In societies where son preference is already strong, violence can deepen the desire for male children, leading to more pronounced son-targeting behavior and potentially more sex-selective abortions.

Understanding these dynamics is important not only for demographic research but also for policymakers and organizations working in post-conflict settings. Recovery is not just about rebuilding infrastructure; it is also about addressing the social norms that conflict can harden. 

Authors Giulia Ferrero and Jessica Mancuso joined the Harvard Center for International Development in Spring 2026 as PhD research fellows sponsored by CID's Visiting Researcher Program. With sponsorship from UniCredit Foundation, this program brings postdoctoral and PhD student researchers from the UniCredit Bank’s extensive European network to CID. Program participants have the opportunity to join CID’s vibrant research community and learn from leading Harvard faculty and researchers.