There’s something satisfying about seeing the same error being made by commentators on the left and the right. In this case, we’re talking about the one-way street fallacy, which is the implicit assumption of unidirectionality in a setting that actually has underlying symmetry.
1. A month or so ago we reported on an op-ed by conservative New York Times columnist Ross Douthat, who was discussing recent research exemplified by the headline, “Study: Having daughters makes parents more likely to be Republican.” Douthat wrote all about different effects of having girls, without realizing that the study was comparing parents of girls to parents of boys. He just as well could have talked about the effects of having sons, and how that is associated with voting for Democrats (according to the study). But he did not do so; he was implicitly considering boy children to be the default.
2. A couple days ago, liberal NYT columnist Charles Blow (link from commenter Steve Sailer) reports on a similar study, this one by Andrew Healy and Neil Malhotra, finding that “that men with sisters are more likely to be Republican. . . . A report from Stanford about the study concluded, ‘Watching their sisters do the chores “teaches” boys that housework is simply women’s work, and that leads to a traditional view of gender roles — a position linked to a predilection for Republican politics.’”
The “report from Stanford” is actually a press release from last year, and it again takes a unidirectional perspective: lots of discussion of what happens to boys with sisters to make them vote Republican, nothing about what happens to boys with brothers to make them more supportive of Democrats. I don’t see any logical reason for brothers to be the baseline, I just think this is how people tend to frame the comparison, without thinking about it. For example, one of the sections of the Healy and Malhotra paper is entitled, “The Effect of Sisters on Political Attitudes,” but there is no corresponding section on “The Effect of Brothers.”
And this framing has an effect, especially in the popular reception of the work, for example in the above-linked op-ed by Charles Blow, who talks all about the effect of sisters while just treating brothers as some sort of gray default, of no interest in itself.
Also (this comes up in the paper and the discussion in a few places), the difference between significant and not significant is not statistically significant.
P.S. When I was a kid, one of my sisters rebelled at one point because she said that the girls got all the gross chores like scrubbing the bathroom. Personally, I hated—hated—mowing the lawn and I swore this would be something I’d never do when I grew up. And indeed I haven’t.