Did the concept of cousinhood exist in Ancient Greece? I JUST learned that Jason and Odysseus were cousins on their mothers’ sides (side note: their grandfather was a master thief?!), and I was wondering if this ever translated into the concept of kinship to the Greeks back then, and if it ever influenced why the two of them had notable similarities (like being known for legendary naval journeys and having flings with powerful sorceresses).
So, on the specifics of Jason and Odysseus: a lot of minor characters in Greek mythology have very different family trees depending on who you ask, and the mothers of Odysseus and Jason are very minor characters. Our main source for Odysseus is, of course, Homer, and Homer says that Odysseus’ mother Anticleia is the daughter of the legendary thief king Autolycus. Now, Homer was probably alive in the 8th or 7th century BC (side note: Homer isn’t real, Google “the Homeric Question” some time; it’s wild, but this is 100% not the time to litigate that $#!tstorm). Our main source for Jason, on the other hand, is Apollonius Rhodius’ Argonautica, which was written in the 3rd century BC, centuries after Homer was dead in the ground (if he was real, which he wasn’t), and Apollonius says that Jason’s mother was Alcimede, the daughter of Clymene, who was herself the daughter of Minyas, the legendary king of Orchomenos – no mention of Autolycus. In addition, though, we have the scholia to Apollonius, which are basically the margin notes made on the text by scholars in the Early Byzantine period (like, 5th to 8th centuries AD), and they are the ones who, quoting other texts now lost to us, give her name as either Polypheme or Theognete and claim she was the daughter of Autolycus. I think the only primary text we actually have that backs this up is a 2nd century BC encyclopaedia of myth attributed to Apollodorus, but he gives yet another name for the mother, Polymede, and he probably got that from Hesiod, who gives that name in his Catalogue of Women but doesn’t explain who she is (at least not in the bits we have, because there is no complete text of the Catalogue of Women and we have to rely on quotations in other authors; are you beginning to appreciate the scope of the insanity we have to deal with here?) (side note: Catalogue of Women is an awful, awful title in the 21st century; it sounds like what a pickup artist calls his diary).
Meanwhile, Homer definitely knows who Jason is and knows the story of the Argo, because the story existed in his time even if our version hadn’t been written down, but he only mentions Jason and his quest in passing and says nothing about his parentage, and the scholia on Homer, who are a different bunch of Hellenistic and/or Byzantine nerds to the scholia on Apollonius, variously say that Jason’s mother is either Alcimede (citing not Apollonius as their authority but Pherecydes of all people, who must be where Apollonius got it from), or Polymele the daughter of Autolycus, or some other dead broad named Eteoclymene, y’know, probably one of those three. And then, you learn that the 1st century BC historian Diodorus Siculus also recounts Jason’s story, but he says that his mother was named Amphinome and also doesn’t specify her parentage, and we don’t get to accuse any of these people of getting the myth wrong or being “confused” because they’re ancient Greeks and we’re not; it’s their mythology, not ours, and their belief is what counts. So… Homer doesn’t specify, and Apollonius – who is the author of the version of Jason’s story that we all actually know – says Jason’s mother is someone different, but a version of that story definitely existed in which Jason was Autolycus’ grandson, except we don’t have that version, and it’s not clear whether Homer knows about it, but if he did then wouldn’t he mention it when Jason’s name comes up in the Odyssey, unless maybe he just didn’t think it mattered?
And don’t even THINK about asking “well, which one is true?” because it’s ALL true, especially the parts that contradict the other parts, and that’s the point, which is something I really think people fundamentally do not get about myth (as the comments on this post will almost certainly demonstrate).
Basically what I’m getting at is “Jason and Odysseus were cousins” is kinda overstating the case somewhat, because neither of the authors of the stories we primarily know Jason and Odysseus from ever said that, it’s not clear where the idea actually came from, and I think any possibility that it might have informed their characterisation is extremely remote (the parallels are probably a combination of coincidence and the reuse of popular tropes in Greek literature, as well as the fact that… well… Apollonius had read Homer and was also writing an epic about a great sea voyage). It’s more like “there’s enough justification out there that you could totally write a fanfic where Jason and Odysseus are cousins, if you want them to be; what’s more, the ancient Greeks would not judge you for it, because the entire concept of ‘canon’ in fiction is a monstrous outgrowth of modern copyright law that is toxic to storytelling and should die in a fire.”
…anyway let’s answer your actual question before I completely lose my mind.
It kinda depends on what we mean by “Ancient Greece.” The vast majority of surviving ancient Greek texts that use kinship terms like “cousin” in clear and unambiguous ways are Athenian legal documents of the 5th and 4th centuries BC, and Classical Athens is a very different world to the mythical world of Jason and Odysseus, which we can… sort of imagine as a memory of the Early Iron Age (say, the 11th through 8th centuries BC) mixed with pastiche of the Late Bronze Age (15th through 12th). So, there is a word ἀνεψιός, which in Classical Athens pretty much invariably seems to mean “first cousin” as we say in English, the child of a parent’s sibling, but in Homer seems more like “relatives” in a broad and general sense. In Athens, kinship terms come up a lot in property law. In particular, Classical Athens has a law which says that, if a man dies without a male heir, his closest male-line relative (often a brother, nephew or cousin) can marry his daughter in order to inherit his estate (women can’t normally inherit property in Athens unless there’s really, definitely no-one else available, because… well, because Athenian law is rabidly misogynistic). On that account, there are quite a few first cousin marriages (and, indeed, many uncle-niece marriages), both out of necessity and even in more normal situations, just to strengthen the bonds of the extended family – so that’s one way the ancient Greek conception of “cousins” doesn’t really map to ours, although of course cousin marriages were still reasonably common in the English-speaking world even in the 19th century, and in some places they are still standard today (for instance, Alabama). Today we kind of have this conception of “cousins” as part of an extended family unit including our grandparents and all their children and grandchildren, where cousins have close relationships as children in the same way siblings do, so that romantic relationships between them are therefore taboo, and I’m fairly confident that that doesn’t exist in ancient Greece. They very much do have, however, a conception of a “clan,” a γένος, that sticks together and supports the interests of all its members and also encourages marriages between its members (which our extended families, at least in the English-speaking world in the 21st century, don’t do), and I would suggest that (in the broad strokes, at least) that’s true both in the Classical period and in earlier, less well-attested eras of Greek history. It’s almost a better comparison to forget the strictly literal meaning and think of the way “uncle,” “auntie” and sometimes “cousin” can be used in, e.g., English-speaking Polynesian communities for friends and their families, even in the absence of blood relations (because this is still in theory a Pokémon blog, we can cite Professor Kukui addressing the player as “cousin” in Sun and Moon, or Hau calling the player’s mother “auntie”).
I hope that answers your question, or at least answers some different, better questions.