Hermaproditism (simultaneous and sequential) and cyclical sex-swapping would seem to eliminate patrilineal and matrilineal concepts of inheritance and allegiance, but I really want one of my alien societies built around the model of great families/clans and major/minor houses.

Inheritance to the eldest offspring or designated heir is easy enough, but without the classic human division of male and female sexes how might it be determined whether an individual is marrying "into" one family and not the other way? Family/house standing can change over time, so relative position probably shouldn't be grounds for deciding and wouldn't help if two families of equal standing are involved. Being the eldest/heir could mean your spouse(s) marries into your family, but what if two heirs are to marry? And what if you, a non-heir, marry "out" of your family and your older sibling (or the designated heir) dies, are you suddenly back "in" your family and your spouse(s) "out" of theirs?


So, how could a hermaphroditic or sex-swapping species produce a society of inter-, extra- and parafamilial alliances and rivalries (i.e. clans, greater and lesser houses, extended kinship) through marriage or some other foundational mechanism?


Background: This is set in a hardish sci-fi universe in which Earth-typical sexual dimorphism and unchanging sexual characteristics are atypical. There are multiple intelligent alien species. While Game of Thrones/ASOIAF would seem to be the inspiration for the society here, I'm actually drawing from The Kindly Ones by Melissa Scott.

  • $\begingroup$ You might read Ursula K. LeGuin's "The Left of Darkness"; she addresses this very subject. $\endgroup$
    – John Feltz
    Oct 7, 2016 at 20:15
  • $\begingroup$ @JohnFeltz You might submit a summary as an answer. $\endgroup$
    – rek
    Oct 8, 2016 at 4:09
  • 1
    $\begingroup$ See also Greg Egan’s Hugo-winning Oceanic, available online $\endgroup$
    – JDługosz
    Oct 8, 2016 at 9:35
  • $\begingroup$ Kinship structures are complex and varied enough among humans where the reproductive roles are stable. With hermaphroditic or sex-swapping species they will be remarkably diverse, complex and variable. Marriage is mainly an economic relationship, aided and abetted by reproduction, so look at the economics to get an idea of the shape of marriage. Research anthropology about kinship, families, marriage, and economics. A very rich & complex field. There are no simple answers. $\endgroup$
    – a4android
    Oct 8, 2016 at 12:10
  • $\begingroup$ I would imagine that the advantage of hermaphroditism in a feudal society is that cuckoldry would be far less of a problem. For example, the plot of Game of Thrones relies on the Queen committing adultery and placing her bastards on the throne, but if the King was the one who gave birth to the royal children then this couldn't happen. In fact it means that the "king" and "queen" could father as many bastards as they pleased so long as either of them birthed legitimate heirs. Said king and queen would be morally repugnant monsters. $\endgroup$
    – Anonymous
    Oct 11, 2016 at 19:04

5 Answers 5


First, this kind of setup doesn't have to eliminate patrilineal and matrilineal inheritances or tracking - there might easily be a distinction between children sired or borne by an individual, and priority given to one over the other as far as inheritance goes (I suspect it would be priority given to heirs born of the body, since that feels like a closer link, even if genetics are nearly the same). A family that has all the children borne by one parent, will be following that parent's clan, a family that has both are just going to have the kids be mirror-claimed by each parent.

Also, if children borne by a person follow their house or clan, and children sired follow their partner's - it might not matter too much which person is marrying into/out of their respective families, since both with maintain their individual standing, and which standing the family as a whole tends to claim will probably depend on both what the relative houses standings are, and what status each individual has in their respective houses. Possibly with the option of going independent or unclaimed, to form a minor household at the very bottom of the social ladder, for those outlying cases where a claim is absolutely unwanted by whoever is deciding.

It would probably be best, I think, either for individual families to choose which claim has priority in a given pairing, or else for the clans or houses to decide between them which one has authority over the pairing. Maybe historically or in conservative clans, the clan has the right to decide if they will claim a pair (and being clan-less or unclaimed is a punishment, exile), and in modern times or liberal clans, the pair decides which clan they will follow (being clan-less is then a protest)? The issues that may come up if a family wants to, or wants not to change allegiance because of relative standing, or of a clan would like to exert or remove a claim (perhaps needing a new heir, or other political shenanigans), are then potential plot elements - especially if changing the primary claim after the fact takes the agreements of everyone involved, or at least two of the three.

Note - this last bit of complicated setup can hold true even if you don't have the sired/borne division of inheritance, it will make for messy familial politics if clans or pairs have to negotiate their claims and the possibility of refusing, or renouncing claims exists, but again - that gives plot-points.

Birth order may play a role in deciding which clan a pair wishes to claim, or relative standing. The choice for a pair to claim as primary the status of heir to a lesser house or minor player in a greater is an honest question, and of course heir can be based on birth order, or not - it can add an extra layer of intrigue the heirs are favored or handpicked by the previous head in a major house (or if each house has their own mechanisms for determining what makes a potential heir, or protocols for what may happen if the head dies without having chosen). What will also play a major role is the individual characteristics of the clans, houses, families, and pairs - staying in a minor house which is friendly or open vs a major house which is backbiting and aggressive in status games is, again, an honest question. Individual occupations may play a role, as the clans may specialize, or value, certain occupations more than others - so a pair or clan may well place a higher value on the claim that more closely matches their interests.


If there is any logic of social dominance within a married couple, regardless of the lack of sex/gender, then most concepts of a traditional gender-oriented society could be adapted. There are infinite possibilities, for example...


The entire culture could be built upon the principle that age is power including within a marriage. So the oldest of the couple would always be the "dominant". When two individuals marry, the younger leaves its family to join the older's.

Social Class

The society is stratified in distinct classes or castes with a linear hierarchy (e.g. nobles > knights and priests > craftsmen and entertainers > peasants) and marriages within one class are forbidden. Social rank defines rights, property and sucession within a couple - so the lowest rank individual leaves its family to join the higher rank one's. Offspring would be assigned to a class at birth or at least before reaching adult age (many possible methods: a) choice by priest, b) first child inherits higher parent's class, other ones inherit lower parent's, c) trials, d) lottery etc.). Once defined, social class is final.

Combat Ability

In a very warlike culture/species, the wedding ceremony could involve ritualistic non-lethal combat. The winner would be the dominant partner for the length of relationship.


It had never actually occurred to me that deciding which family you are joining was a reason for gender-specific inheritance in the first place, and I'm not sure it's historically and cross-culturally true even in us non-hermaphrodites.

Primogeniture just means "inheritance of the first-born", with stipulations around gender an addition which varies across cultures in time and place. Primogeniture is really not about marrying "into" or "out of" families: it's not the status of the spouse that matters, but the status of the children. In short, what titles and privileges do they stand to inherit, which their parents inherited in turn?

Let's say Al, the first-born child of house Li, marries Bo, a lesser child of house Ka. Li inherits a major Duchy, whereas Bo is given a minor title and a few estates. Their only child, Cho, stands to inherit both claims, but clearly the Duchy will be their most important inheritance.

It might be that, due to the disgrace of house Li, Cho decides to style themselves as the first of a new dynasty: the first Ka Duke. Or, for political expedience, they might try to forge a new house of Li-Ka, encouraging their cousins to intermarry and unite the houses.

If Cho marries Dee, of house Mu, who also inherits a duchy, things look different again: their first child, Eed, will inherit both titles; the minor titles might be distributed to other children. The new united Duchy will either become a powerful united force, under the Li-Mu, or Ka-Mu dynasty, or it will fragment, with rival claimants on either side plotting to wrest one or the other title from Eed and their descendants.

Any number of combinations are possible, and European history is full of wars fought because of them, and there's no need for gender to play a role at all.


This may be a great opportunity for you to revisit existing dynamics regarding families.

For instance, maybe marrying heirs is how families signify that they want to merge. Or married couples form their own "pod" that has different rules until some ritual let them integrate a family (this could be born out of the need for exogamic behaviors in a species that can produce as many females as it wants).

Or this species could have developed genealogy into a science and wouldn't look at families the same way we do: different groupings would be relevant for different occasions (economy, war, art, religion, etc.). Maybe they could have evolved senses to perceive how they relate to one another (pheromones?) or developed complex fashions to signify ancestry.

This world provides many interesting storytelling ideas.


I think your problem does not need to be a problem. All these "undecided" things could move your story along because they give rise to social conflict.

In medieval Europe, the heir was well-defined. That did not stop younger brothers or even sisters from trying to get their own. And families with only daughters would have a son-in-law, or even an uncle, inherit. All this led to a lot of scheming and GameOfThrones-like antics.

So I suppose you could go with some simple method to decide on the heir for a house (for example the "Age" answer that dnep gave). A couple where neither partner inherits would just need to start their own house (probably of low standing, and they may need to make up a new family name because their older siblings do not want to be associated with a much lower house). This gives room for a lot of maneuvering/politics among siblings (either subtle or violent), competition for "good" partners (which leads to a certain sexual culture: either very free or very restricted), etc etc.

What will your marriage laws be like? I remember Orson Scott Card's "Homecoming" series where marriages need to be renewed or dissolved every once in a while. Or maybe you're using arranged marriages as a plot device.

Will this lead to population control laws? Or certain forms of birth control? Or will couples be able to determine the future of their children to a much greater extent than humans. For example, it might be legal to banish/disinherit/kill your child if they commit a certain transgression. My advice: think carefully of ways to climb the social ladder, possible religious influences, and the marriage / birth control practices in this culture.


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