These's not a word in abstract of the study [0] that they have controlled for anything. (and I don't say that assuming anything about a study is a bad scientific practice, but I do assume it)
>one would assume they controlled for this. Its a scientific study.
My priors have shifted in the opposite direction over time. When I hear studies like this I'm tempted to assume mediocrity in both the collection and analysis of the data that puts the results into questionable utility for me. And not just mediocrity but potential bad faith tricks like p-hacking and its cousins.
It would take a substantial effort from high quality scientists (meaning individual reputation) including replication studies to get me interested.
[0] https://onlinelibrary.wiley.com/doi/abs/10.1111/dar.13239