Even though sexual relations are considered different now than in the Middle Ages, people across time have always dealt with similar issues, just in different ways. For example, people have oft tried to figure out how to have intercourse without getting pregnant. People have the same concerns about performance or lack of experience. And people have been scared about the prospective sinfulness of their intimate lives for centuries. Literally. Regardless of geographic location or point in time, those actively engaged in intimate relations have also shouldered concerns about sexual health and prosperity.
Although society's perspective on sexuality may have changed since the Middle Ages, some details of how people got down to business are surprisingly still relevant. Albeit, the reasoning may not be quite so similar. How people sexually interact may have changed throughout the centuries, but fundamental principles still ring true: humans are drawn to the exploration of the body and the pleasures it may afford.
It wasn't until the late 11th century that the Roman Catholic Church began to impose celibacy upon its clergy. Before this, priests could marry and were also expected to raise their sons to be priests as well. By this time, however, the Eucharist was becoming increasingly sacred.
The notion that priests could take a roll in the hay with their wives and then touch the altar and sacrament didn't sit well with higher-ups in the Church.