Sexuality in space habs

If you had only one habitat, or if you had several where each
had little turnover in residents, then inbreeding might be a
problem. But if you have dozens, scores, hundreds of
habitats, and if the populations mix it up somewhat (*), then
the number of people moving into your habitat, moving out of
your habitat, and all those people from other habitats you
meet at that convention every year, will give you plenty of
choices.

You won't have to have a "reproduce with people from
elsewhere" rule; that will tend to happen fairly often by
default. And even the people "from here" will be a diverse
lot, with all kinds of "elsewhere" genes.

(*) vacationing in other habs, business flights to other habs, moving to another hab for job, family, or cultural reasons; and of course people from all over winding up in your hab for all the same reasons