This world invisaged the institution of marriage differently due to most male infants being born dead. Marriages would occur between sister-wives, who would share a man between them. This form of marriage would take the form of a collection of woman-woman unions, with the male serving as a partner. These marriages between women wouldn't be sexual, but seen as a pragmatic solution that provides a stable way for them to have children and build lineages. It is common to marry a business partner to combine professional interests, or a political ally to build relationships and power blocks. All children produced within this group marriage would belong to that family, with lineage passed down through matrilineal lines.

These unions could extend to two or more women, but be limited to one husband to prevent conflict between families over reproductive rights. This makes patrilineal lines so important, because they are the only familial ties that connect all the siblings together when the women are not related. However, as there are so few men in society, it would make more practical sense to seek as many relationships as possible to secure a lineage. This would incentivize wives to seek lovers outside of their respected "vows". As there would be no way to determine who the real father is, this would be impossible to regulate.

In our world, when a spouse cheats on a partner, it is customary to leave the relationship. However these unions were not based on emotional commitments, but business relationships or to satisfy political realities based on power. as such, it would be a weak excuse to end it. Since these unions combine resources and assets to form a cohesive family, it would be difficult and costly to extract oneself from the relationship that you have invested in.

How can you discourage these kinds of relationships outside of group marriages?

  • $\begingroup$ Why would just having widely accepted social norms not work? $\endgroup$
    – Topcode
    Commented Feb 11, 2022 at 2:43
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    $\begingroup$ I think you're mixing up your terms. Monogamy comes from the Greek for single marriage. By definition a group marriage isn't monogamous. $\endgroup$
    – sphennings
    Commented Feb 11, 2022 at 2:51
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    $\begingroup$ Why would they actually need to discourage them actively? The issues with virginity and fidelity in patriarchal societies mostly stemmed from the males being unsure whether they are really the father. Here the women would always know they are the mother of their heir. Sure, 'poaching' on husbands of other women will be frowned upon, but it will be something that happens from time to time. $\endgroup$
    – Cumehtar
    Commented Feb 11, 2022 at 3:15
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    $\begingroup$ Treating anybody in a marriage as a "second-class" partner seems a great way to encourage infidelity. Since these marriages are not based upon emotional attachment, infidelity would not be a wrenching emotional betrayal. In short, the only tools you have left seem to be cultural mores...which seems inadequate. Love and sexual attractions can overcome cultural mores. Whole Shakespeare plays are based on that. $\endgroup$
    – user535733
    Commented Feb 11, 2022 at 5:11
  • $\begingroup$ Why would it make sense to have a patriarchal lineage in such a world? Seems like it's much easier to track matrilineal lines than patrilineal ones. If men are scarce wouldn't it make sense to form family units that didn't revolve around them? $\endgroup$
    – sphennings
    Commented Feb 11, 2022 at 8:20

7 Answers 7


Reproduction For Hire:

Inheritance from the matrilineal line means that you already know who the mother is. This is why being Jewish is tracked via the mother - you always know who the mother is. But you want siblings who are related even if the females in the marriage AREN'T related, and for that you need consistent male input. But your families don't REALLY seem to want the men there. So what to do?

It sounds like men are a rare commodity. Scarcity is the mother of capitalism.

If the men are second class, cut them out of the marriage entirely and have them manage careers as studs (in this case, entirely literal - reproduction for hire). A family simply hires the appropriate male, and he inseminates as many women as they can afford. Hire him or a close male relative of his for additional children who will then be related through the patrilineal side as well. If you want a guarantee, then have a contract with the male promising to provide repeat services. Or even better, if technology permits, use a sperm bank. A man could then sell the rights to sperm in repeated applications, even as he aged out of the viable production years.

Infidelity becomes a moot point - either the women are having sex with each other or not. Sex for reproduction becomes an entirely contractual affair. If you don't want unrelated children, use birth control. But men can afford to be picky, and asking them to give it away is a lot to ask for.

Obviously, laws would need to be written to assure services, but such laws for patrilineal descent have dominated the formation of many cultures for centuries. There would be no problem getting such laws written. If paternity testing is available, then this can be used to assure women haven't gone "free range" to get sperm on the cheap (free).

  • Men and Marriage: If a family does want to have a man in the family, it's likely to be a more equitable arrangement based on family, and not based overly on sex (although there may be some). A man might marry his sister's or even his mother's family to secure his inheritance to hers, and potentially offer his services gratis to his non-related wives. That way, he still enjoys the social structure of family, but it's not about sex (save for that occasional really awkward love thing that might come up, and then it gets fun and complicated from an author's point-of-view). A man's wives would likely manage his career, In a matronizing manner, possibly giving discounts to other families as a way to manage alliances and assure genetic relationships between friendly families. The real poaching would be women (as a family) trying to lure a man away from his mother and sisters.
  • Genetics: In a world with many females and few males, there is a fair risk that people will end up having children with half-siblings and not know it. Having a system of stud means that you can track who's father was who's, and be assured that your potential mate didn't have the same father. So even without testing, you're reasonably sure your dad was stud 728 ("Bill") and the donor stud 1243 ("Ted") weren't related. It also means that if a genetic disorder turns up, you can track it easily (in grad school, I heard about a case where a single German sailor with a genetic marker for a disease had 300+ offspring by having a wife/girlfriend/mistress in every port, but I don't have the documentation to prove that...)
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    $\begingroup$ Stopping the man cheating can then become a matter of contract. If you’re currently engaged under a contract with an exclusivity clause the financial repercussions of infidelity could be quite large. $\endgroup$
    – Joe Bloggs
    Commented Feb 11, 2022 at 14:22

First, a few notes:

  • Polyandry: one woman married to multiple men.
  • Polygyny: one man married to multiple women.
  • Polygamy: (despite popular belief), multiple women married to multiple men. This word has become the "catch all" when it comes to describing non-monogamous marriage despite the rarity of polyandry and true polygamy. Consequently, most people who hear the word will actually be thinking about polygyny.

And now a Frame Challenge

It's a good thing you're only looking to discourage affairs, because your biggest problem with polygamy is that the only way to enter into a polygamous relationship is to do exactly what you're trying not to do: enter into relationships outside of marriage. Given that many societies in our world today favor shacking up as a prelude to marriage, it's difficult to see how you could possibly justify no external relationships. So, to throw a few rules out that might help with discouraging the practice:

  • Social morality states that there can be no sexual relationships outside marriage. I.E., "wait for the wedding night." Given that world history has proven that to be an unrealistic social expectation save (and only to a degree) in highly religious communities, this won't be much help.

  • You invoke adultery laws. To wit, the law strictly enforces the nature of marriage and marital relationships, criminalizing adultery. While no European countries criminalize adultery, there are still 17 U.S. states that do — although (according to the linked article) prosecutions are rare. But, marry (every pun intended) adultery laws with some form of fascism and Bob's your uncle. Or your second husband. It depends.

  • You make the community highly religious. This is basically the first bullet with a kinda-tried-and-sometimes-works method of imposing a specific morality: religion. If you think about it, this is nothing more than combining the first and second bullets.

  • Trivially (and I'm not trying to be trite with this one), you can imprison the husband in that the wives form a family council that closely monitors the activities of the husband. Call this one bullet-number-two-lite.

In a world where there are few men and a lot of women, I would assume the men would be in high demand. (Wasn't there an episode of Sliders about a disease that killed all but one man in a world full of women?) It would be realistic for said men to have their freedoms seriously curtailed for the good of society — in other words, they'd be put out to stud a lot, lest society not have enough replacement men. Which was kindof the storyline of that show I just mentioned.

I wondered if my answer was equally applicable to both the men and women in Incognito's question. I believe the answer is yes, though it's a complicated question as to whether one would be more likely to enter into an affair than the other. Given enough wives, the men would have little reason to stray (in fact, that's one of the reasons modern Christian polygamists give to justify the practice). On the other hand, the more wives there are in the relationship, the less intimacy any one wive can expect over a period of time. That could be some serious motivation to go poaching. And to make things worse, the greater the ratio of women-to-men, the more likely men would be compelled to the first marriage early in their lives — literally as an effort to reduce the idea of victimless poaching. This issue can get really messy really quickly.

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    $\begingroup$ The Sliders episode had few men, who spent all their time as studs. It was actually the inspiration for my answer! sliders.fandom.com/wiki/Love_Gods $\endgroup$
    – DWKraus
    Commented Feb 11, 2022 at 13:51
  • $\begingroup$ Polygynandry (otherwise known as group marriage in humans) is the system where both men and women have multiple spouses, polygamy is just the generic multiple spouses that can be used to describe any of the configurations $\endgroup$
    – LuizPSR
    Commented Feb 11, 2022 at 15:11
  • $\begingroup$ @LuizPSR I can't find the word "Polygynandry" in the Merriam-Webster dictionary. I can find the definitions for Polyandry, Polygyny, and Polygamy. $\endgroup$
    – JBH
    Commented Feb 11, 2022 at 17:17

However these unions were not based on emotional commitments, but business relationships or to satisfy political realities based on power.

This sounds like medieval Europe for non-peasants. So you just need to add one extra component from that time into the mix.


Have a church watch over and regulate such marriages. This will make the church very powerful, and then the church will try to exert absolute control over marriages in order to keep its power.

If all the population is loyal to this church, they can show how warmly faithful they are by burning cheaters at the stake. This has the advantage of maintaining a thriving entertainment industry as well.


A few issues need to be worked out in this system.

How would a young woman be transitioning from her parental family to a new family? In modern world, where nuclear family is dominant, young people are forming couples and can immediately reproduce. In historic world with extended families and clans, women (or sometimes men) were married into their spouses' family where they also could immediately start reproducing.

In this proposed sister-wives world, it appears that "wives-family" must reach certain size before they can marry a man. If, as it said, woman would congregate with business partner or a political ally, this means there will be a long time before they can reproduce. In a world where rate of stillbirths is high, this is a very detrimental feature.

How we can work around this limitation (while keeping extramarital affairs forbidden)?

  1. Rejuvenating families (or rather, clans). Young women would join an established clan (which likely already has a husband as well as older women) where she can get pregnant and have children. Later, this clan will pick up younger women, bury the old ones (hopefully after long and happy life), and pick up younger husbands when necessary. Note that this approach would need some mechanism to provide care for for older, non-performant husbands.

  2. Graduating families. At some reasonably young age (18), young women are expected to form groups (Families? Clans? Circles?) with their female peers. After these groups are formed, they would compete for for husbands, and form full families which would hopefully last into old age.


Practically this is polygyny. As told here

Most Christian groups have historically rejected the practice of polygamy and have upheld monogamy alone as normative.

Therefore church will never allow this.

Regulation of polygyny

As told here, Polygyny is allowed in Islam and it regulated with very strict rules. Under these rules or laws, any sexual relation outside marriage (by man or woman) is considered as sin, immoral in society and has punishment by the court.

You can discourage these kinds of relationships outside of group marriages by making laws against such practices with punishment by the court and by making it immoral in the society.


Ink mark genitals.

It is customary for each woman to have a unique set of sticky, wash resistant paint on their genitals. Any woman without such paint is seen as incredibly slutty and promiscuous and is socially shunned. Each paint is unique in colour and smell and taste. If you have sex with someone outside marriage you'll tend to leave a mark on them of this paint.

Genital checks are common, and denying one from an elder is seen as a massive social faux paux. As such, infidelity to the point of having children is quite rare because of the large consequences. If your paint is discovered on another man that is grounds for divorce, and to be kicked out of your village for your wild sexual ways.

Infertility is handled with public sex.

If a man can't impregnate their wives they'll be pressured to have sex in public a number of times to prove they are doing it right. If they fail for several months, they can be declared infertile and the marriage dissolved.


Non Problem

I challenge your point that for women "it would make more practical sense to seek as many relationships as possible to secure a lineage."

From the evolutionary point of view, the cost of carrying a child is so great that the woman is better off spending time selecting a single strong male than sleeping with as many males as she can.

Women who are happily in relationships have no evolutionary incentive to spread themselves around. They might still have affairs but no more than with married couples. Unmarried women on the other hand are encouraged to have affairs with married men since they are in short supply. Men are also encouraged to impregnate everything that moves.

From the societal point of view, a married woman sleeping with a man other than her husband does not help her establish a lineage, since any child resulting from such an affair will be assumed to have been fathered by her husband. You have solved your own problem.


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