6 ms·

No, we've understood heredity for a very long time, and sex between siblings or between parents and children has always been a taboo. Cousin marriage, however,

No, we've understood heredity for a very long time, and sex between siblings or between parents and children has always been a taboo. Cousin marriage, however, is not particularly harmful (https://www.psychologytoday.com/blog/animals-and-us/201210/the-problem-incest https://www.psychologytoday.com/blog/animals-and-us/201210/t...). The real reason we stopped marrying cousins is: 1. We started to live in large cities instead of on farms and ranches. (https://www.census.gov/population/censusdata/table-4.pdf https://www.census.gov/population/censusdata/table-4.pdf) 2. We could reasonably travel more than 10 miles from home in a day. In other words, we used to marry cousins because it was too difficult to find better prospects.

rflrob 9y ago
I haven’t yet read the scientific article that it’s based on, but the OP points out that there’s about a 50 year lag between the move to cities and a decrease in cousin marriage, so there was probably some cultural component.
- da_chicken 9y ago
  Oh, certainly. Any culture takes time to develop a taboo like that. It's especially hard to damn the behavior of your own parents when their union led to your own existence. Only when everybody who was married has died will there really be a change.
- Parcissons 9y ago
  Im expecting a game of throne spike very soon in those statistics.
alva 9y ago
"The real reason we stopped marrying cousins is:..." Perhaps in the majority groups in the West. Certain communities in the UK still widely practice cousin marriage and suffer hugely in genetic abnormalities. They are not constrained by transport, it is a cultural thing that has not yet been updated.
- petercooper 9y ago
  Two of my great-grandparents were first cousins. We blame every bit of nuttiness in our family on this, whether or not it's fair :-D
  - blueblimp 9y ago
    Though close relatives marrying is bad for the children's health, it's actually a slight benefit for the grandchildren, great-grandchildren, etc. Why that's true: The reason inbreeding is bad is that the child is at risk of inheriting two copies of a nasty recessive mutation, in a region of their genome where both versions came from the same recent ancestor. However, if the child goes on to successfully reproduce, it's more likely that they had zero copies than two--and in that case the grandchildren have zero copies, which is good for them.
- smellyindian 9y ago
  Based on the cultural sensitivity on display, I am going to guess you are Brit, and are referring to the Pakistani rat children? The practice is sometimes constrained by foiling kidnappers at airports, so yes, transport is certainly not a limiting factor at all.
  - 2trill2spill 9y ago
    > Pakistani rat children That seems rather harsh. Or is that a real term? Either way it seems like a rather harsh term to call a child.
    - omarqureshi 9y ago
      Yeah, that's not a real term ...
    - deleted 9y ago
      [deleted]
    - deleted 9y ago
      [deleted]
walrus01 9y ago
extensive scientific evidence contracts your claim that it is "not particularly harmful": http://www.bbc.co.uk/bbcthree/article/6af25e7b-0545-42ba-a6fa-82ac1023b4ed http://www.bbc.co.uk/bbcthree/article/6af25e7b-0545-42ba-a6f... http://www.bbc.com/news/uk-england-leeds-23183102 http://www.bbc.com/news/uk-england-leeds-23183102 http://www.independent.co.uk/life-style/health-and-families/health-news/health-why-cousins-can-be-just-too-close-the-pakistani-practice-of-marrying-relations-may-be-causing-1483250.html http://www.independent.co.uk/life-style/health-and-families/... http://blogs.jpmsonline.com/2015/12/07/cousin-marriages-a-public-health-issue-in-pakistan/ http://blogs.jpmsonline.com/2015/12/07/cousin-marriages-a-pu... https://www.ua-magazine.com/first-cousin-marriage-doubles-risk-of-birth-defects/ https://www.ua-magazine.com/first-cousin-marriage-doubles-ri...
- foldr 9y ago
  The issue there is probably with the practice being common and repeated through many generations. The risk of generic abnormalities is not particularly high for cousin marriage.
  - walrus01 9y ago
    yes, a single instance is not extremely risky from a statistical perspective, it's when the children of first-cousin marriages repeat the practice for several dozen generations... some really bad things can crop up.
    - Retric 9y ago
      Even that's not enough, you need a small population, small number of children each generation, and for harmful mutations not to be weeded out. A wild Frog species that has 100 eggs could have regular 'first-cousin' marriages without significant issues beyond infectious diseases. Humans unfortunately tend to accumulate negative mutations more easily. Though the upside of lack of predation etc is not something I would want to pass up personally.
iguy 9y ago
"2. We could reasonably travel more than 10 miles from home in a day." No, this is not the reason. Plenty of societies had very strong norms against cousin marriage centuries ago -- from memory below 1 percent in colonial new england? Others did not. Sometimes because they were just far from the enforcers of such norms. But often for deliberate reasons of keeping family and property together. Saddam Hussein wasn't short of private jets, but was very concerned about losing power, and blood relatives are more reliable. And about 50 percent of his countrymen feel the same way.

rflrob 9y ago

I haven’t yet read the scientific article that it’s based on, but the OP points out that there’s about a 50 year lag between the move to cities and a decrease in cousin marriage, so there was probably some cultural component.

da_chicken 9y ago
Oh, certainly. Any culture takes time to develop a taboo like that. It's especially hard to damn the behavior of your own parents when their union led to your own existence. Only when everybody who was married has died will there really be a change.
Parcissons 9y ago
Im expecting a game of throne spike very soon in those statistics.

alva 9y ago

"The real reason we stopped marrying cousins is:..." Perhaps in the majority groups in the West. Certain communities in the UK still widely practice cousin marriage and suffer hugely in genetic abnormalities. They are not constrained by transport, it is a cultural thing that has not yet been updated.

petercooper 9y ago
Two of my great-grandparents were first cousins. We blame every bit of nuttiness in our family on this, whether or not it's fair :-D
- blueblimp 9y ago
  Though close relatives marrying is bad for the children's health, it's actually a slight benefit for the grandchildren, great-grandchildren, etc. Why that's true: The reason inbreeding is bad is that the child is at risk of inheriting two copies of a nasty recessive mutation, in a region of their genome where both versions came from the same recent ancestor. However, if the child goes on to successfully reproduce, it's more likely that they had zero copies than two--and in that case the grandchildren have zero copies, which is good for them.
smellyindian 9y ago
Based on the cultural sensitivity on display, I am going to guess you are Brit, and are referring to the Pakistani rat children? The practice is sometimes constrained by foiling kidnappers at airports, so yes, transport is certainly not a limiting factor at all.
- 2trill2spill 9y ago
  > Pakistani rat children That seems rather harsh. Or is that a real term? Either way it seems like a rather harsh term to call a child.
  - omarqureshi 9y ago
    Yeah, that's not a real term ...
  - deleted 9y ago
    [deleted]
  - deleted 9y ago
    [deleted]

walrus01 9y ago

extensive scientific evidence contracts your claim that it is "not particularly harmful": http://www.bbc.co.uk/bbcthree/article/6af25e7b-0545-42ba-a6fa-82ac1023b4ed http://www.bbc.co.uk/bbcthree/article/6af25e7b-0545-42ba-a6f... http://www.bbc.com/news/uk-england-leeds-23183102 http://www.bbc.com/news/uk-england-leeds-23183102 http://www.independent.co.uk/life-style/health-and-families/health-news/health-why-cousins-can-be-just-too-close-the-pakistani-practice-of-marrying-relations-may-be-causing-1483250.html http://www.independent.co.uk/life-style/health-and-families/... http://blogs.jpmsonline.com/2015/12/07/cousin-marriages-a-public-health-issue-in-pakistan/ http://blogs.jpmsonline.com/2015/12/07/cousin-marriages-a-pu... https://www.ua-magazine.com/first-cousin-marriage-doubles-risk-of-birth-defects/ https://www.ua-magazine.com/first-cousin-marriage-doubles-ri...

foldr 9y ago
The issue there is probably with the practice being common and repeated through many generations. The risk of generic abnormalities is not particularly high for cousin marriage.
- walrus01 9y ago
  yes, a single instance is not extremely risky from a statistical perspective, it's when the children of first-cousin marriages repeat the practice for several dozen generations... some really bad things can crop up.
  - Retric 9y ago
    Even that's not enough, you need a small population, small number of children each generation, and for harmful mutations not to be weeded out. A wild Frog species that has 100 eggs could have regular 'first-cousin' marriages without significant issues beyond infectious diseases. Humans unfortunately tend to accumulate negative mutations more easily. Though the upside of lack of predation etc is not something I would want to pass up personally.

iguy 9y ago

"2. We could reasonably travel more than 10 miles from home in a day." No, this is not the reason. Plenty of societies had very strong norms against cousin marriage centuries ago -- from memory below 1 percent in colonial new england? Others did not. Sometimes because they were just far from the enforcers of such norms. But often for deliberate reasons of keeping family and property together. Saddam Hussein wasn't short of private jets, but was very concerned about losing power, and blood relatives are more reliable. And about 50 percent of his countrymen feel the same way.