Why Mothers Prefer Daughters, Fathers Prefer Sons

Women are more likely to invest time and energy in daughters than sons, according to a new study that also shows men have a slight preference for male offspring. Statistically speaking, daughters win the day, but sons win dad by a nose. These findings are somewhat surprising, given the prevailing theory that preference for sons or daughters is based less on the sex of the parents than on their socioeconomic status.

“Our study failed to show that the parents’ preferences for the offspring’s gender are affected by their status, wealth, education or childhood environment,” said co-author on the study Robert Lynch of the University of Turku, Finland, in a statement. “Instead, parental preferences were best predicted by their sex. Women from all socioeconomic backgrounds expressed implicit and explicit preferences for daughters: They chose to donate more to charities supporting girls and preferred to adopt girls. Men expressed consistent, albeit weaker, preferences for sons.”

Lynch and colleagues set out to test the Trivers-Willard Hypothesis, an old social science chestnut that predicts wealthier parents will prefer sons and bias their investment toward boys, while poorer parents focus on daughters. In order to stress test this idea, the researchers asked 347 women and 423 men to read a script that was designed to make them feel either wealthy or poor. Those within the wealthy condition were asked to think about how they differed from those at the “bottom of society,” who are “the worst off” and have “the least money.” Those within the poor condition were prompted with the opposite language, and asked how they differ from those at the top. (An unfortunate control group was asked to write five sentences about the weather.)

After being primed to consider themselves part of a caste, each participant indicated an adoption preference between little girls and little boys, a preference between charities benefitting little boys and little girls, and finally a bald-faced sex preference. The researchers were surprised to find that none of the economic conditions seemed to matter. Whether primed for wealth, poverty, or weather forecasting, women preferred girls and daughters across the board. Men showed no preference for adoption, a modest preference for donating to help girls, and a slight implicit bias for boys and sons.

Part of this can be explained by the fact that, at least in the Western world, daughters are increasingly in vogue. “Overall, parents now invest more in daughters than they do in sons,” according to the study. “Prospective couples are 45% more likely to express an interest in adopting daughters over sons…[and] since 2008 there has been a sharp decrease in the likelihood of native-born Americans having another child after the birth of a daughter, suggesting either an increase in preferences for daughters or a decrease in preferences for sons.”

Still, it could be socioeconomics in disguise. The authors speculate that, since wives tend to have less access to shared funds than husbands, women may perennially express their preference for daughters due to their own “poverty” just as the Trivers-Willard Hypothesis predicts. “By focusing on sex differences in access to household resources, we may gain insight into why mothers and fathers in the same household might differ in their investment in daughters and sons,” the authors conclude. “Our finding that females exhibit a preference for daughters may be the consequence of females having lower access to shared resources than males.”