Daughters get a lot more parental time investment than sons in reading, storytelling, and teaching of letters and numbers. This was the finding of a study done by Michael Baker of the University of Toronto and Kevin Milligan of the University of British Columbia called "Boy-Girl Differences in Parental Time Investments: Evidence from Three Countries" released this March. The researchers found that moms and dads in the United States, Canada, and the United Kingdom engaged in these teaching activities more with their little girls as early as nine months old.
The study, published by the National Bureau of Economic Research, also revealed that the gender difference is apparent in such activities as taking the kids to the library, giving them books, and reading to them. In these areas, parents gave more time to their daughters than their sons.
In an NPR interview with host David Greene, Baker says: "When we looked at specific activities -- what we call teaching activities; so this would be, how often do you read with your child or, how often do you teach them the alphabet or numbers -- systematically, parents spent more time doing these activities with girls."
The researchers found that "the observed differences are not due to a direct preference of parents for children of a specific sex at these ages." In fact, the researchers found that the disparities in time investment exist even when parents of fraternal twins aimed to treat them similarly.
So if it's not preference, what could possibly explain the difference in time inputs? One reason is the high cost of teaching sons. Cost here does not refer to money but to the effort involved. Baker explains: "The costs of providing these inputs are different for boys and girls. So for example, it is just more costly to provide a unit of reading to a boy than to a girl because the boy doesn't sit still -- you know, doesn't pay attention, these sorts of things."
Although still a hotly contested topic, another explanation is that girls are more inclined to cognitive activities than boys. Moreover, the "cultural scripts and unconscious biases" that parents follow which basically entails doing more active play with their sons can also explain the reason for the disparity. These, however, still need to be further studied.
The parental investment in cognitive activities may help explain why girls in elementary schools in the United States generally perform better in tests. While there is a modest difference in the preschool cognitive scores of boys and girls in the study, the researchers conclude that the "the impact may cumulate at older ages if learning deficits and advantages are cumulative." Furthermore, they acknowledge that "parental teaching may embed behaviour patterns that children need to excel at school... [and could even] precipitate patterns in children's own use of time at older ages."