by Charles Panati

During European feudal times, all public announcements concerning deaths, taxes, or births were called “banns”. Today we use the term exclusively for an announcement that two people propose to marry. That interpretation began as a result of an order by Charlemagne, king of the Franks, who on Christmas Day in A.D. 800 was crowned Emperor of the Romans, marking the birth of the Holy Roman Empire.
Charlemagne, with a vast region to rule, had a practical medical reason for instituting marriage banns.

Among rich and poor alike, a child’s parentage was not always clear; an extramarital indiscretion could lead to a half-brother and a half-sister marrying, and frequently did. Charlemagne, alarmed by the high rate of sibling marriages, and the subsequent genetic damage to the offspring, issued an edict throughout his unified kingdom: All marriages were to be publicly proclaimed at least seven days prior to the ceremony. To avoid consanguinity between the prospective bride and groom, any person with information that the man and woman were related as brother or sister, or as half-siblings, was ordered to come forth. The practice proved so successful that it was widely endorsed by all faiths.