I assume you are referring to family pressure?
Some but not only.
Outside of "pray the gay away" American silliness from some Churches I don't think I see much pressure to marry with the opposite sex
I hear it a lot -- I live in the US, I grew up in mostly liberal areas of it (and live in one now) and it's still very common for me to hear, both in person and in media, the idea that queer people are confused, deviant or mentally-ill. I don't tend to hear the suggestion that they're demon-possessed outside of more "churchy" circles than I habitually frequent, but I do run into the attitude from time to time since I have a fair bit of contact with multiple culture groups in my everyday life (and pretty much all of them have their own flavor of homophobia).
What I was going for is that the social reality of homosexuality in some parts of the ancient world as it likely was has both ups and downs when compared to the social reality of homosexuality in the West today
Sure, I agree with you.
and that comparison to them is hard to use that as an argument that all modern societies are extremely intolerant of homosexuality.
Well, I didn't mean to make that point by means of the comparison, but I do think it's a true statement -- I genuinely if you were to round up all the distinct societal groups in the world today (however you want to slice the distinctions -- I'd say it's true at both the level of communities and nation-states), you'd find that a big majority of them display homophobic/heterosexist norms. That's not to say it's the same kind or intensity everywhere, but my life as a queer person has left me rather disillusioned with the idea that even places with a reputation for "tolerance" or "acceptance" (say, a liberal city in Canada, which I've spent plenty of time in, and where same-sex marriage is just a thing, or the Netherlands, which I haven't visited but have some friends from) are really, at a basic statistical level, not homophobic. I agree that in some places those norms have shifted so greatly that it's not a major thing there, but I don't think those places are really representative of the majority of human social groups or cultures, however finely-grained your definition of those things.
One of the lessons highlighted in the thread "Less Wrong NYC: Case Study of a Successful Rationalist Chapter" is Gender ratio matters.
There have recently been a number of articles addressing one social skills issue that might be affecting this, from the perspective of a geeky/sciencefiction community with similar attributes to LessWrong, and I want to link to these, not just so the people potentially causing problems get to read them, but also so everyone else knows the resource is there and has a name for the problem, which may facilitate wider discussion and make it easier for others to know when to point towards the resources those who would benefit by them.
However before I do, in the light of RedRobot's comment in the "Of Gender and Rationality" thread, I'd like to echo a sentiment from one of the articles, that people exhibiting this behaviour may be of any gender and may victimise upon any gender. And so, while it may be correlated with a particular gender, it is the behaviour that should be focused upon, and turning this thread into bashing of one gender (or defensiveness against perceived bashing) would be unhelpful.
Ok, disclaimers out of the way, here are the links:
Some of those raise deeper issues about rape culture and audience as enabler, but the TLDR summary is:
EDITED TO ADD:
Despite the way some of the links are framed as being addressed to creepers, this post is aimed at least as much at the community as a whole, intended to trigger a discussion on how the community should best go about handling such a problem once identified, with the TLDR being "set of restraints to place on someone who is burning the commons", rather that a complete description that guarantees that anyone who doesn't meet it isn't creepy. (Thank you to jsteinhardt for clearly verbalising the misinterpretation - for discussion see his reply to this post)