LOL. You're going to dismiss the study because of the justification for doing the study. Here, let me help you understand:

"not fully understood" -> "so we studied it" -> "here's what we found"

Besides that obvious point, the sentence you quoted says "not yet fully understood," not "we have no idea." Those aren't the same thing. We actually have substantial evidence pointing in a clear direction.

- The most egalitarian countries show the largest gaps, not the smallest. - Women exposed to elevated androgens in utero become more things-oriented despite being raised normally as girls. - Male and female monkeys show the same toy preferences we do. Nobody's socializing rhesus monkeys into gender roles. - A 1.28 standard deviation gap in every culture that emerges in infancy and grows as societies get freer is not what socialization looks like.

You're treating "not fully understood" as "both hypotheses are equally supported."

They aren't.

The evidence overwhelmingly favors a substantial biological component. Just because you don't like the implications of that, doesn't make it false.

Seethe harder.