Apr 27, 2025 12:11 AM
(This post was last modified: Apr 27, 2025 12:38 AM by C C.)
PRELUDE: Ironically, the Catholic Church may be historically responsible for weaning the West from incest. "Not marrying cousins" is a WEIRD cultural attribute. Consanguineous relationships were common in ancient pre-Christian times, and still lingeringly are in other parts of the world. European throwbacks like Darwin and Einstein both did the deed in the 19th and 20th centuries, respectively (albeit the latter did not reproduce with his 2nd wife.)
https://www.mcgill.ca/oss/article/inbree...ind-stigma
EXCERPTS: . . . The parents were cousins, and they had married each other around the time this child was born. It seemed likely that the mother had become pregnant out of wedlock, which in this tightly knit community was frowned upon, and she was quickly paired up with her cousin to preserve appearances.
These two married cousins went on to have children of their own, many of whom were affected by this disease.
Hollywood often presents inbreeding as proxy for body malformations and, subsequently, as an indication of evil. Movies like The Hills Have Eyes, The Texas Chain Saw Massacre, and the Wrong Turn series show us antagonists that are either explicitly or implicitly inbred—and living in rural areas, notably the American South...
[...] But what do we actually know about the consequences of inbreeding? There is a big myth to address first: that inbreeding is rare. It’s actually quite common.
The scientific term we use is “consanguinity,” which comes from the Latin for “from the same blood.”...
[...] Shockingly, consanguineous couples and the children they have make up one out of every ten human beings on planet Earth. Far from being limited to Appalachia and to Amish communities, consanguinity is common, especially in North Africa, the Middle East, and South Asia, and there are plenty of reasons for this.
In many communities, marrying a cousin can be seen as strengthening family ties; as avoiding the health or financial uncertainties of tying the knot with a stranger; and as reducing the risk of your spouse abusing or deserting you. Consanguinity can even be encouraged by religion: it is sanctioned by Judaism and Buddhism, with Islam remaining ambiguous and Christianity having conflicting attitudes toward it...
It’s easy to think that most people would avoid inbreeding, but worldwide that is not the case; even animals rarely steer clear of it, as was shown through scientific research.
But if we are to understand the reason why many fear consanguinity, we have to talk about genetics.
[...] Second cousins share 1/32nd of their genes. First cousins once removed—where one of them is the child of the other’s cousin—share 1/16th of their genes. That fraction changes to 1/8th for first cousins and to 1/4th for half-siblings, uncle-niece pairings and aunt-nephew pairings. A parent and their child or any pair of siblings will share half of their genes. If diseases run in the family that require both copies of a gene to be mutated, a child’s chance of inheriting these diseases goes up when their parents are consanguineous.
Scientists have attempted to study the real-life consequences on disease and fertility of consanguinity among humans. The risk is real, but how bad is it really?
There is a long list of birth defects that have been linked to consanguinity in the parents, and it includes sensory issues like hearing loss and visual impairment, as well as neural tube defects and heart disease. The problem is that many of the studies that have reported on these associations have failed to look for other explanations.
[...] I think it’s fair to say that children born of a consanguineous union are more likely to inherit a medical condition, especially if their parents are very close relatives, but that the problem is not as bad as Hollywood pretends it is for shock value. In animals, given enough time and enough consanguinity, the situation can turn into “inbreeding depression” — which has nothing to do with the mental health of mice but rather announces a drop in survival and fertility within an animal population when too much of the progeny is inbred.
I am also reminded of the concept of a “founder effect,” which is when a community is founded by very few people, and everyone ends up descended from them. If one of the founders had a genetic condition, it will become common among their lineage. It’s not because everyone is encouraged to marry their cousin, but simply because the starting population is small, so genetic diversity is limited.
Inbreeding is useful in research, believe it or not...
[...] I’m certainly not trying to encourage people to look at their cousin through a different lens. In fact, consanguinity also includes unions between underage children and their older relatives, which I would argue are ethically indefensible. But there is stigma and dramatization around the issue of consanguinity, which can be harmful.
[...] Consanguinity is less common than it used to be thousands of years ago, as societies have industrialized and migrated toward large cities, but it does remain quite common, especially in certain parts of the world. Because specific genetic disorders run in certain populations, diagnostic tests are available (and in some places mandatory as part of premarital screening programs) to help inform couples looking to have kids. By destigmatizing the reality of consanguineous unions, we’ll be in a better place to help a large chunk of the world’s population... (MORE - missing details)
How the early Christian church gave birth to today's WEIRD Europeans (2019)
https://www.science.org/content/article/...-europeans
EXCERPT: The church's early ban on incest and cousin marriage, the researchers say, weakened the tight kinship structures that had previously defined European populations, fostering new streaks of independence, nonconformity, and a willingness to work with strangers. And as the church's influence spread, those qualities blossomed into a suite of psychological traits common today across Western industrialized nations, they argue...
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https://www.mcgill.ca/oss/article/inbree...ind-stigma
EXCERPTS: . . . The parents were cousins, and they had married each other around the time this child was born. It seemed likely that the mother had become pregnant out of wedlock, which in this tightly knit community was frowned upon, and she was quickly paired up with her cousin to preserve appearances.
These two married cousins went on to have children of their own, many of whom were affected by this disease.
Hollywood often presents inbreeding as proxy for body malformations and, subsequently, as an indication of evil. Movies like The Hills Have Eyes, The Texas Chain Saw Massacre, and the Wrong Turn series show us antagonists that are either explicitly or implicitly inbred—and living in rural areas, notably the American South...
[...] But what do we actually know about the consequences of inbreeding? There is a big myth to address first: that inbreeding is rare. It’s actually quite common.
The scientific term we use is “consanguinity,” which comes from the Latin for “from the same blood.”...
[...] Shockingly, consanguineous couples and the children they have make up one out of every ten human beings on planet Earth. Far from being limited to Appalachia and to Amish communities, consanguinity is common, especially in North Africa, the Middle East, and South Asia, and there are plenty of reasons for this.
In many communities, marrying a cousin can be seen as strengthening family ties; as avoiding the health or financial uncertainties of tying the knot with a stranger; and as reducing the risk of your spouse abusing or deserting you. Consanguinity can even be encouraged by religion: it is sanctioned by Judaism and Buddhism, with Islam remaining ambiguous and Christianity having conflicting attitudes toward it...
It’s easy to think that most people would avoid inbreeding, but worldwide that is not the case; even animals rarely steer clear of it, as was shown through scientific research.
But if we are to understand the reason why many fear consanguinity, we have to talk about genetics.
[...] Second cousins share 1/32nd of their genes. First cousins once removed—where one of them is the child of the other’s cousin—share 1/16th of their genes. That fraction changes to 1/8th for first cousins and to 1/4th for half-siblings, uncle-niece pairings and aunt-nephew pairings. A parent and their child or any pair of siblings will share half of their genes. If diseases run in the family that require both copies of a gene to be mutated, a child’s chance of inheriting these diseases goes up when their parents are consanguineous.
Scientists have attempted to study the real-life consequences on disease and fertility of consanguinity among humans. The risk is real, but how bad is it really?
There is a long list of birth defects that have been linked to consanguinity in the parents, and it includes sensory issues like hearing loss and visual impairment, as well as neural tube defects and heart disease. The problem is that many of the studies that have reported on these associations have failed to look for other explanations.
[...] I think it’s fair to say that children born of a consanguineous union are more likely to inherit a medical condition, especially if their parents are very close relatives, but that the problem is not as bad as Hollywood pretends it is for shock value. In animals, given enough time and enough consanguinity, the situation can turn into “inbreeding depression” — which has nothing to do with the mental health of mice but rather announces a drop in survival and fertility within an animal population when too much of the progeny is inbred.
I am also reminded of the concept of a “founder effect,” which is when a community is founded by very few people, and everyone ends up descended from them. If one of the founders had a genetic condition, it will become common among their lineage. It’s not because everyone is encouraged to marry their cousin, but simply because the starting population is small, so genetic diversity is limited.
Inbreeding is useful in research, believe it or not...
[...] I’m certainly not trying to encourage people to look at their cousin through a different lens. In fact, consanguinity also includes unions between underage children and their older relatives, which I would argue are ethically indefensible. But there is stigma and dramatization around the issue of consanguinity, which can be harmful.
[...] Consanguinity is less common than it used to be thousands of years ago, as societies have industrialized and migrated toward large cities, but it does remain quite common, especially in certain parts of the world. Because specific genetic disorders run in certain populations, diagnostic tests are available (and in some places mandatory as part of premarital screening programs) to help inform couples looking to have kids. By destigmatizing the reality of consanguineous unions, we’ll be in a better place to help a large chunk of the world’s population... (MORE - missing details)