According to a study published in the Science Magazine, the actions and conduct of the Catholic Church during the Middle Ages (476-1492) have influenced the behavior of Western Europeans to this day, especially with regard to marriage and family structures.
During the medieval period, the Church was the largest landholder in the West, setting itself as one of the great authorities of its time.
According to the study, these Church Decrees made much of the WEIRD population replace their close relationships with their relatives, with smaller and more independent families.
This kind of behavior would later have been transmitted to the descendants of these peoples, who consequently became more individualistic and more likely to relate to complete strangers.
Remember that the descendants of these societies were responsible for invading and colonizing North and South America between the fourteenth and eighteenth centuries (from XIV to XVIII).