Mothers
prefer daughters and fathers prefer sons
University of Turku
Finnish and American researchers in evolutionary
biology conducted an online experiment and survey which reveals that women
prefer and are more likely to invest in their daughters and men in their sons. The study was designed to test the impact of parental resources on offspring sex preferences.
Specifically, the authors sought to
test the Trivers-Willard hypothesis which predicts that parents in good
conditions will bias investment towards sons, while parents in poor conditions
will bias investment towards daughters.
"However, our study failed to show that the parents' preferences for the offspring's gender are affected by their status, wealth, education or childhood environment. 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. In contrast, men expressed consistent, albeit weaker, preferences for sons," explains lead author, Postdoctoral Researcher Robert Lynch from the University of Turku, Finland.
The researchers tested the
Trivers-Willard effect with an online experiment by measuring implicit and
explicit psychological preferences and behaviourally implied preferences for
sons or daughters both as a function of their social and economic status and in
the aftermath of a priming task designed to make participants feel wealthy or
poor.
The results of the research help to
make sense of the often contradictory findings on offspring sex preferences. The
effects of parental condition and status, competing genetic interests between
males and females, economic constraints on families, and the effects of
cultural practices all conspire to complicate the evolutionary outcomes of
parental investment strategies.
"Frequently, the impact of one
factor, for example, the genetic sexual conflict between males and females, can
mask the impact of another, such as the Trivers-Willard Hypothesis. This can
make it difficult to parse their effects and make clear predictions about
'optimal' parental investment strategies from an evolutionary perspective. We
hope that our study can shed new light on these strategies and provide a better
understanding of evolutionary biology in humans," states Lynch.