By Ryan Morrison For Mailonline
Published: 09:41 GMT, 8 November 2019 | Updated: 13:21 GMT, 8 November 2019
The Medieval Catholic Church's 'obsession' with preventing incest could have triggered the rise of 'individualism' in modern Western society, a new study reveals.
Traditional cultures and clans tended to remain fiercely loyal, with extended family marriages and a fear of outsiders, according to research by the American Association for the Advancement of Science.
But that started to change in Western societies in the 9th Century, when the Catholic Church changed its policy on who could get married, effectively banning close relatives from tying the knot.
The rules split apart previously tight networks and forced communities to cast their nets wider for marriage partners, embracing outsiders and new alliances.
As a result, the team found that Western industrialised countries tend to be more individualistic, analytical, rich and democratic than other cultures around the world.
The number of cousin marriages in the west has been declining since the middle ages when the Catholic Church changed its policy on inter-family marriages
As part of the study into the origins of this shift in society they found that around the 9th Century the Catholic Church changed its policy on who could be married.
They say that the church moved from requiring couples wishing to marry to have a family tie to eventually banning anyone with family ties from marrying.
Dr Jonathan Shultz, one of the authors on the research paper told the Daily Telegraph: 'I was surprised just how preoccupied medieval Europe was with the fear of incest. Historians also talk about an obsession with incest.
'This fear was not only about incest with close relatives but included an ever-expanding circle of cousins, in laws, spiritual kin such as godparents and godchildren. Natural disasters such as the plague were attributed to God's punishment for incest.'
He said it is thought the family structure and society in western Europe was similar to the rest of the world before the change in the Catholic Church's marriage laws.
The number of cousin marriages in the west has been declining since the middle ages, whereas in countries in the Middle East and elsewhere the rate has remained steady, Dr Shultz said.
The study highlights how cultural changes more than 500 years ago can evolve and seed significant and