Similarly, as noted above, ancient myths and religions offer no clear guidance on the issue either. But if we are to argue that the practices of ancient people provide justification for modern institutions, then I suppose Strabo can help us out, for he describes single-gender societies that raise children in (presumably) same-sex households, deigning to visit the opposite sex only out of biological necessity, unable to stomach even looking at them, and wholly without heterosexual marriage:
The Gargarians also, in accordance with an ancient custom, go up thither to offer sacrifice with the Amazons and also to have intercourse with them for the sake of begetting children, doing this in secrecy and darkness, any Gargarian at random with any Amazon; and after making them pregnant they send them away; and the females are born are retained by the Amazons themselves, but the males are taken to the Gargarians to be brought up; and each Gargarian to whom a child is brought adopts the child as his own, regarding the child as his son because of his uncertainty. (11.5.1, trans. H. L. Jones)
On a completely different topic, I would be remiss if I didn’t note my disappointment that the Syfy channel Greek mythology series Olympus chose the least imaginative route to resolve its fantasy about the activities of the gods in Mycenaean Greece. In this week’s episode, the Greek gods and the Titans were revealed to be space aliens (or possibly interdimensional beings), proving that the program’s unimaginative writers watched too much Ancient Aliens, whose wacky claims they appear to have borrowed wholesale. There’s nothing wrong with the idea per se (except that Star Trek did it five decades ago), but it clashes with the Immortals-style fantasy tone the show strived for in its low-budget retelling of the myth of Theseus.