Actually, when you come to think of it, this isn't such a bad idea, especially for the one in 100 children in the US today born with ambiguous genitalia. Well, quite a few, given our rates of divorce and remarriage. Some children can point to a dozen grandparents. In my opinion, only a woman could have written these books. There are no machines whatsoever, anywhere.
Transport is by snail-like animals called tilios.
Houses and rooms are organically grown, with shapes and spaces that can be changed at will. Everyone is superbly nourished on vegetarian, genetically-engineered, food. Butler's characterization of humans draws on some urban African-American experiences. The Oankali try to provide this through environment, training, and ultimately genetic merger - though it's a bit hard to see what they themselves get out of it. They can and do cure a host of genetic disorders, whose names are liberally spread about in the final volume.