The link between hypergamy and matronarchy
Note: As usual in the following when in the following for brevity there are definite statements, they should be interpreted as to probabilities, not as universal laws, because in human behaviour there are many nuances.
The fundamental principle of human society life is "the mother is always certain, the father never" (which is still largely true despite the possibility of DNA testing, which has anyhow been made practically illegal in some countries, "to protect mothers from violence").
The secondary principle of human society is that bearing and rising children is risky and expensive and slow, while impregnation is mostly safe, cheap and quick.
This means that, especially before modern times, having daughters or sons has different consequences:
Daughters: generate less income than sons, but their children are guaranteed to continue the genetic lineage of their grandmothers, even if they will be expensive and few.
Sons: their children are not guaranteed to continue the genetic lineage of their grandmothers, but if the sons are very attractive they will be, and will be cheap and many, and if the sons are faithful and hardworking they will support their mothers on old age.
This means that the main strategies available to would-be mothers are:
Choose as fathers pump-and-dump players (which makes them attractive as likely to have many children) a woman can have sex with, and "prefer" the birth of sons.
Sex will be very pleasurable for the mothers.
The mothers will likely have many grandchildren for their genetic lineage.
The mothers having to bear and raise their sons on their own.
The mothers will be later being left alone and poor in old age by both the fathers and their sons.
Choose as partners and fathers faithful hardworking men (which makes them unattractive as less likely to have many children), and "prefer" the birth of sons.
This will likely result in the bearing and raising of children being largely funded by a man.
The mothers will be supported in her old age by the sons.
Sex will be disgusting for the mothers.
The sons will likely be unattractive as their fathers, so there is a large risk that most of the grandchildren of their mothers actually be fathered by attractive pump-and-dump players.
Choose as partners unattractive faithful hardworking men, and as fathers attractive pump-and-dump players, and "prefer" the birth of sons.
This will likely result in the bearing and raising of children being largely funded by a man.
Those sons will be likely attractive pump-and-dump players who will give their mothers many grandchildren continuing their genetic lineage.
In case of discovery the mothers will likely lose the support of their faithful hardworking partners.
In any case in old age the mothers are unlikely to be supported by their pump-and-dump player sons.
Choose as partners and fathers faithful hardworking men (which makes them unattractive as less likely to have many children), and "prefer" the birth of sons and at least one daughter and Ensure that their unattractive, reliable, loyal, hardworking men sons marry virgins trained and repressed by their mothers to accept sex with unattractive but worthy men and be faithful (at least to some extent) to them.
Sex will be very pleasurable for the mothers, except for the few cases they will have to give it to their partners.
The mothers will be supported in their old age by their partners and sons.
The daughters will guarantee with some grandchildren the continuations of the genetic lineage of the mothers.
The sons will have grandchildren more likely to continue the genetic lineage of their grandmothers, especially the first borns.
The mothers will have to train and repress their own pump-and-dump player sons, if any, to be reliable, loyal, hardworking partners, in order to be acceptable as son-in-law to other mothers.
The mothers will have to train and repress their own daughters to accept sex with unattractive but worthy men and be faithful (to some extent) to them, in order for their daughters to be acceptable as daughters-in-law to other mothers.
Sex will be disgusting for the mothers (and their daughters).
The mothers won't have as many grandchildren belonging to their lineage as if they had chosen as fathers pump-and-dump players.
Note: The strategy of choosing proven pump-and-dump players as fathers who miraculously turn into faithful hardworking partners just for them is the dream of every would-be mother, but they know it is very unlikely: the attractiveness of those pump-and-dump players is largely because they have a strong ability and drive at scattering their seed around.
The last listed strategy is that of the "matronarchy", and it is the matronarchy that has resulted in the sexual and social repression of both women and of the successful pump-and-dump players they are sexually attracted to.
The link between hypergamy and the "matronarchy" is therefore grandchildren: in order to have a good chance of being supported by their children in old age, yet have grandchildren belonging to their genetic lineage, mothers and grandmothers have to reject hypergamy, for themselves, for their daughters and for their sons with a pump-and-dump player instinct, if any, by creating a sexually and socially repressive culture, the "matronarchy".