Tbh, it might actually be no one. For one, these are some of the most professional people on the planet - wildest deviations I can think was someone smuggling a sandwich on board, and one of them bringing a gorilla costume.
Two, a lot of being an astronaut is pretty undignified when it comes to waste management, and they can’t just take a shower, so I’d wager whatever sponge bath they’re able to pull off likely leaves a lot to be desired. So, not really prime sexy time.
And physically, sex in zero-g seems like one of those things that sounds fun on paper, but in practice would be a lot of work to the point of not being worth the effort.
…I do wonder what zero-g would do to gestation and development, especially over the course of multiple generations. Probably the kind of thing we should start with mice though - humans take too long.
The soviets tried letting rats breed in zero g but they didn’t seem to manage to copulate. A number of smaller organisms have been able to breed in zero g and/or microgravity including c elegans, fruit flies, and cockroaches. They have shown that mouse IVF is at least theoretically possible (petri dish embryos are possible) but it doesn’t seem that they’ve tried actual breeding since that soviet rat experiment.
