The single largest factor affecting sexual practices in the Republic is, of course, the Soul Tax itself. The Tax falls disproportionately on young, marriageable males, especially among the lower and poorer classes of society. Before the Precepts of Ruthlessness and the Alexian Restoration, the Tax was even more brutal than it is today, culling up to 50% of a generation’s young men in a sweep. Thus societies long under Denayi rule tended to develop (with the encouragement of the Circle) polygamy as a way of ensuring that women of childbearing age obtain access to a spouse. The resultant family was matriarchal, and consisted of several cohabiting women, with or without a male. Inheritance passed through the mother. Some households of women had no official spouse, but rather each woman alternated abstinence and pregnancy with an available male.

By contrast, those with wealth and power practiced monogamy as a status marker. In these unions, the male (who was often part of the local or Denayi government) predominated. Legitimacy of title passed only through the legal wife. The husband, of course, was often unfaithful, but chastity was expected of his wife and any concubine. Divorce was possible, but as this invalidated many legal arrangements, it was discouraged.

In the centuries of Denayi’s long decline, and then in the years since the Alexian Restoration, the Soul Tax has fallen more lightly on the subject worlds, and the Denayi pattern of polygamy has become less necessary. Some extremely poor and hard-hit communities continue to practice it, as do extremely conservative areas and Worlds, and it is still recognized in law, but recent years have heightened its association with poverty and backwardness. Thus monogamy of a form similar to modern America and Europe has come to predominate.

In most societies, women with the material means to support children face strong but not always insurmountable pressure to do so, either from their culture or in the form of tax penalties.  On most Worlds, however, they are legally free to remain unmarried, practice birth control, or pursue celibacy, if that is economically viable for them.

If monogamy stands as a form of status marker in the Republic, then male homosexuality represents the ultimate form of conspicuous consumption, for in such a relationship neither partner contributes to the birth rate. In a society which relentlessly consumes its own population, only the most wealthy and powerful can engage exclusively and openly in such activities. Homosexual relationships are most common among the nobility and the Uukaptai, and usually follow a pattern of age differentiated roles similar to early modern Europe. The older partner is usually the active one, the younger one the passive partner. These same roles also act as a form of patronage, especially among the Uukaptai. The passive role carries with it a stigma of effeminacy that increases with age, and is considered more appropriate for a boy than a man. Denayi society considers any male past his late twenties engaging in passive sex as deeply shameful. The active role carries with it the taint of the decadent, but is tolerated among persons of a certain station -- a young, privileged male has quite a bit of license. Beyond a certain age, however, every male is expected to settle down and marry. Any noble male of thirty-five who has not sired children is not fulfilling his social duty. Monogamous male homosexual unions are therefore almost unheard of, except perhaps among the Uukaptai, where they are often derisively called an "Uukaptai marriage."