In most developed countries, girls do better than boys at school. There’s a ton of evidence for this - see here, here, or here. This hasn’t always been the case - girls’ grades have been getting a lot better over time. Even in subjects where boys are often thought of as performing better than girls (like maths), I think the evidence generally suggests that girls actually outperform boys at school, but the effect size is smaller than for other subjects. That’s the finding from Voyer and Voyer’s meta-analysis, in which they note that:
I'd be interested in seeing data for a non-US country for gay/lesbian college attainment, because the US seems to have a strong norm of moving out in order to attend college (Australia less so, because so much of the population is situated in urban centres). If you're selecting for the group of students who are most strongly motivated to leave home for several years (and potentially never go back), I'm not surprised if you get a bunch of gay/lesbian/trans people who are out. The other possibility is that the security of having a degree and being in relatively liberal areas enables gay people to come out (they'd be closeted if they didn't get the degree).
My personal experience in Australia is that LGBT uni students are slightly overrepresented in rural/ interstate students compared to urban. My personal experience is potentially also slightly skewed by my time on lesbian Tinder where it seemed like every other girl I matched with was from the country, so I'd be interested if anyone has any hard numbers.
I think the advantage for homosexual men is because of higher average IQ.
RE the girls a better suited to school due to conscientiousness, agreeableness argument.
How has school changed over time that this has flipped from boys to girls?
On the one hand, school has become less strict. Which could go either way - being conscientious and agreeable probably makes you relatively better suited to strict schooling. But at the same time, perhaps stricter schooling helps the less naturally disciplined, ie boys.
Another angle is a change that I don't really have a word for, but I think is definitely there. I'd describe it as a move towards taking the variance out of exams and results. Examples would be increased teaching to test, and clearer guidelines on and consistency of exams. This benefits the methodical and conscientious over other traits.
All that said, I think it's culture - what's expected of you? what are the social pressures?
I have also researched and read theories on why this is true. More than one study posits that the traditional classroom setting is not always best suited for boys and their inherent testosterone-driven behaviors. This manifests in boys' inability to sit still for long periods of time, spontaneous aggressive interactions ("acting out") .. and other maturity issues. These traits also seem to naturally connect to the "agreeableness" gap. As a former teacher, I can at least offer anecdotal evidence that hormonal differences may be a factor.
Although thanks for presenting all these learned studies believe I’ll claim direct observation and trust my gut here. As a mom I’ve always shuddered at the cruelty of putting all curious, creative, athletic young children in classrooms the way we do. Boys especially need the large muscle activity of active play and thrive on outdoor participation involving their imagination. Girls do to. But especially these kids benefit from Socratic education - interaction with grounded, intelligent adults who know how and why to hold a conversation. The most intelligent, well-functioning adults I’ve know hated elementary & high school and just managed to benefit from, yet overcome their higher educations.
Here is another thought: what if we can correlate labor productivity (in USD) against agreeableness, IQ/SES/Education and average salary? Maybe there is a social sinktrap that puts compliant but talented people into high-output low-demand positions. Weirdly enough maybe we can spot inverse talents (rebellious smarts) within this frame.
See also: "Clueless" from Gervais Principle. [Opportunists], in their own best interests, knowingly promote over-performing [Populace] into middle-management (the "cluelessness" within the essay), groom under-performing [Populace] into [the opportunist caste]. https://www.ribbonfarm.com/2009/10/07/the-gervais-principle-or-the-office-according-to-the-office/
Submissive types enjoy being told what to do and are more dutiful, which is what school rewards with higher grades. Feel free to broadly categorize gays, lesbians, men, women as more or less submissive. You’re probably right on average.
Over time, school success is more focused on consistent assignment completion and process and not subject mastery. I have a feeling that tilts the playing field against boys, who are more likely to not follow the prescribed process as they achieve mastery.