There's "common knowledge" that people in certain professions (or with other particularly unusual traits) tend to date/marry/have kids with others who are the same. To a certain extent this is always common; it's a guaranteed shared interest, and any profession provides a decent way to meet other people. However, certain professions have a reputation of having this be much more pronounced, presumably because either the profession encourages people have a take on humanity that's fairly unusual or because there's some general disrepute or othering that's part of the profession. For example, actors (and agents), carnies, lawyers, musicians, psychologists.. I wonder if this has remained constant over time or if we've come to segment more or less. Presumably things like the internet make it easier for society to auto-segment (although for some of these, where the profession becomes significantly hereditary and part of a lifestyle, it was presumably always segmented to begin with). At the same time, if we have more social mobility (not just social class, but professionwise) with general education, I would expect to see the subcultures of the professions diminish a bit.
Bringing it down to my personal life, I've mostly dated people of what I'd call the academic caste of American society; people whose lives are primarily organised around ideas rather than building concrete things (or software) that are directly productive, often in the public sector. I'm pretty happy with that; I could imagine dating people outside it, but there's a cultural gap that'd require some navigation (I didn't really get on with the IndyHall people because while they're geeks too, they're geeks with a business sense who seemed to be as hungry for money as for geekery. They probably could smell academia on me as much as I could smell business on them, and we mostly didn't smell right to each other.
One concept I mentioned recently in some debates, the political-philosophical intuitions of technolibertarianism, is relevant here; it's a set of intuitions that strongly reject centralisation of decisions, with the intent to organise society so as to the maximal benefit of the technically inclined and sophisticated elite who have the entrepreneurial gusto to go out, start businesses, and change society. It's one form of petit-bourgeois thought that resents some but not all parts of government; it's not strictly minarchist, nor necessarily friendly to megacorporations, but almost universally seeks to serve the interests of small, flexible businesses and economic flexibility. Geeks tend to divide along these lines; some of us (like me) represent the traditions of control, guarding and tending the flame of civilisation and celebrating the infrastructure that makes knowledge possible (many but not all of us are socialists), others represent the interests of the enlightened individuals who seek to tear down old, pre-knowledge-centric worldviews, and embrace radical diversity and the freedom to fail. The culture clash is pretty rough (Eric Raymond was my first exposure to a prominent technolibertarian who talked about it as such); while when I was younger I was reasonably technolibertarian, the tendencies of each exposes us to the other and I eventually moved over the line. The technolibertarian who provides infrastructure is the dictator of that infrastructure and tends to its users (a bulletin board, a club, a company), which produces the mothering instincts that are central to those of us who are technosocial. The technosocialists often find themselves breaking laws or agitating against them when they stand against productive change, and use the tools and communities of the technolibertarians to aid them in that.
Of course, these are not opposites. There are many other worldviews that the two sides of geek society tend to face together. Still, I've seen groups and circles of friends tend to autosegment on this once they leave university and hit the real world (even as they often land in different parts of the real world).