Marriage Between Cousins
It is estimated that 20 percent of all couples worldwide are first cousins. It is also estimated that 80 percent of all marriages historically have been between first cousins.
Greece and Italy
The majority of European countries, including Greece and Italy, allow marriage between first cousins. However, in more religious regions this is greatly frowned upon, and in the Catholic Church marriage between first cousins is prohibited.
Marrying one’s cousin in Ancient Greece was not only not frowned upon, it was encouraged, and sometimes drafted into family law to ensure that children marry cousins in order to preserve the bloodline. Not until advances in modern medicine did awareness of genetic birth defects arise.