"It's - not actually unusual in nonmagical, less-than-cosmopolitan societies, where people aren't magically changing sex all the time, for the general consensus to be that everybody should get heterosexually married and have kids. A lot of people want to do that anyway, when it's a live option, and it's a pretty stable social norm compared to polygamy or making everybody sex-segregate or dealing with a lot of single mothers and rootless men or other things you could try to have be standard. - men are somewhat more likely to be violent or criminally inclined in general in a large population, and also aren't by default on the hook for dealing with a baby if one occurs. Adding gay people - or accommodating the range of possible preferences of multisexual people - doesn't necessarily threaten this structure, but it notably isn't this structure, and structures like that are in large part sustained by soft coercion or sometimes stronger forms of insistence, applied without a lot of fine discrimination. Things loosen up with better technology like contraceptives and treatments for sexually transmitted diseases and enough wealth that the household isn't the basic economic unit of society - you guys aren't technologically advanced but you could in theory have only one person in every city eat or sleep at all, that frees up enormous amounts of time and resources, and you use some of them on making it convenient for more people to sleep and eat but you don't have to and nonmagical people absolutely have to or they will die, and when your household is organized into an interdependent unit and somebody leaving threatens that it's much more important to everyone involved to enforce the responsibilities the individuals have to the group. And I'm from a loosened up place, so everyone was always fine with it, that I'm gay. And Kyeo's planet is not loosened up. They have some of the technology but they're trying to do communism with it and it doesn't work very well and also separately for historical reasons Ibyabek is kind of maniacal about everybody having children."