The OP didn’t link to a peer-reviewed well-designed study. They linked to a “news” article that purports to relay the information from the study, but no doubt presents much of it out of context and to an audience who lack the expertise to really understand it.

I was referring to men vs. women, or gays vs. straights, or residents vs. immigrants, or any one of the hundred other arbitrary divisions being constantly foisted onto us.

The study may well be measuring these divisions, or their effects, but that’s not my point at all.