Prohibition of incestuous marriage (consanguinity and affinity) was not an original product of medieval thought, but, rather, has ancient origins. It was banned under classical Roman law, which medieval canon law (the law of the church) later inherited. The prohibited degrees of kinship fluctuated greatly in both the classical and medieval periods, however, depending on social, legal, and economic needs. The purpose of these laws in ancient Rome was not meant to impose religious morality or to control sexual acts, but to regulate social order since intermarriage within certain degrees of kinship had legal implications for inheritance. Classical Roman Law—developed around the time of the first century CE—did permit Roman citizens to marry their first cousins (fourth degree of kinship), whereas earlier iterations of Roman Law were more restrictive. Although legal under Classical Law, marriage to first cousins does not necessarily appear to have been the norm.

The Christianization of the West added theological implications to inherited classical laws governing marriage and sexuality, which, of course, included incestuous marriage. Marriage was seen as an indissoluble covenant— meaning divorce as we know it today didn't exist—but this covenant had to be entered into properly or it was considered null. The Bible included multiple condemnations of incest, however, it was unclear on which degree of kinship was permissible for marriage. In addition to Christian theology, as with Classical Roman Law, there were social and economic incentives for curbing consanguineous marriages in early and central medieval Europe (ca. 600–1000). The church, which had grown in centralization and power by the eleventh century, sought to prevent its property from falling into the hands, and thus inheritance, of ambitious noble families. Given these historical developments, as canonists (scholars who wrote on canon law) and jurists developed more defined canon law over the course Middle Ages, they sought to impose clearer guidelines for which degrees of kinship were permissible for marriage. By the eleventh century and by the time the church actually gained some degree of legal jurisdiction over marriage regulation (the governing authority of the church should not be overestimated, especially in the early Middle Ages), it was largely agreed that marriage was not permissible within the sixth or seventh degree of kinship (roughly, second cousins once removed, etc). This expansive prohibition was likely best for the church's economic interests. By the time of the Fourth Lateran Council in 1215, Pope Innocent III and his council lowered the acceptable degree from the restrictive seven to four (first cousins, etc), likely to curb the number of annulment suits. Calling consanguinity law a "ban" is a bit of a misnomer, since couples could appeal to the pope for special dispensation to marry within the conventionally prohibited degrees.

It's difficult to pinpoint one thing that led to the rise of individualism; however, one example is perhaps the growing emphasis on pastoral care after the Fourth Lateran Council. Speaking in broad terms, thirteenth-century Europe experienced a wave of lay religious fervor. Lay people (people who were not part of the religious or secular clergy) increasingly sought individual expressions of faith through relics, increased access to preaching, private devotional materials, such as Books of Hours written in both Latin and vernacular, veneration of saints, etc. The reasons for this include the expansion of literacy in the twelfth and thirteenth centuries and economic growth. The church, while regulating lay expressions of faith, also sought to meet these demands. Therefore, some of Lateran IV's most lasting reforms expanded lay access to faith expressions and sacraments. After 1215, priests were required to serve Eucharist to their entire congregation at least once a year and parishioners were required to attend private confession at least once a year. Priests were likewise expected to provide comprehensive spiritual care for their parishioners, and bishops were tasked with overseeing that priests were performing according to ecclesiastical expectations. This is not to suggest that the church always enforced these ideals in practice; however, these trends suggest that the cultural tide of western European Christianity had begun to shift from more corporate expressions of faith to a growing concern for inner devotion.