Where our family is from the priests wouldn't allow marriage between 6th cousins. My grandfather was 6th cousins three times removed from my grandmother. (so she was 9 generations away from common ancestors with him) They had to get written permission from the bishop to get married.
The Church worked very deliberately over centuries to reduce the influence of families / clans, in some places more successfully than others. It all revolves around inheritance rights and accumulated power. (Also in some cases the Church could collect money by charging for exemptions.)
The beauty of selective enforcement. Dig deep enough into your ecclesiastical data-monopoly and you can veto just about any marriage at will. It never was the same again once laymen started to read and write.
Yes, it was the Franciscans who were a huge influence and kept record of these things.
Most people would remember relations as far as great-grandparents and relations to families/family friends that they knew. Literacy was pretty high in the region early on as well, but people continued to rely on the church for recordkeeping.
