
When Did Americans Stop Marrying Cousins? Ask the World’s Largest Family Tree - dnetesn
https://www.nytimes.com/2018/03/01/science/cousins-marriage-family-tree.html
======
slavik81
The Economist had a special report on marriage a few months back with a bit on
cousin marriage around the world. They had an interesting conclusion.

> Two academics, Bilal Barakat and Stuart Gietel-Basten, point out that when
> women usually have five surviving children, a woman can expect to have 25
> male cousins. When the average number of children falls to two, that same
> woman will have just three male cousins, some or all of whom might be
> younger than she is, and thus ineligible as marriage partners. The marriage
> squeeze will be even tighter in cultures that insist, for example, that a
> woman marry not any old cousin but her father’s brother’s son. Eventually,
> cousin marriage will be crushed not by medics but by mathematics

[https://www.economist.com/news/special-
report/21731490-pract...](https://www.economist.com/news/special-
report/21731490-practice-cousin-marriage-doomed-consanguineous-marriages-are-
declining)

~~~
dalbasal
Interesting! I'd never thought of cousin availability as a factor.

But....is it actually possible to average much over 2 children for very long?
I mean, that's a population boom.

~~~
jhbadger
Definitely yes. Pretty much the case throughout most human history. Somewhat
countered by the high rate of infant/children death though.

~~~
anovikov
But not much more than 2 children surviving through marriage age. That would
mean a total population explosion in less than a century. Definitely wasn't
ever the norm: population used to be more or less constant through mid-XVIII
century.

~~~
skj
Side comment, but using Roman numerals to indicate century is completely
bizarre to me.

~~~
DanAndersen
It seems to be a thing in various continental European regions. I'm most
familiar with seeing it done in French. From Wikipedia:

>Capital or small capital Roman numerals are widely used in Romance languages
to denote centuries, e.g. the French xviiie siècle[26] and the Spanish siglo
XVIII mean "18th century". Slavic languages in and adjacent to Russia
similarly favour Roman numerals (XVIII век). On the other hand, in Slavic
languages in Central Europe, like most Germanic languages, one writes "18."
(with a period) before the local word for "century".

~~~
jhbadger
And the famous Mexican beer Dos Equis gets its name because it was created in
1897 and was celebrating the soon to be 20th century (XX, Dos Equis in
Spanish).

------
epx
My grandpa married his second cousin, it was already frowned upon in 1935 but
not unheard of. One improvement factor was transportation - the bicycle was
invented not much before, and it was expensive. But a bike or a train ticket
allowed you to know people beyond the rural village you lived. It's been even
said that the inventor of the bicycle was the 2nd greatest feminist, because
he improved the availability of suitable grooms, nobody needed to marry the
violent moron next plantation anymore.

~~~
soperj
Queen Elizabeth married her first cousin from one side and second from the
other. Not frowned upon in certain circles...

~~~
olliej
Royalty is literally defined by marrying into your own family — essentially
all royal families in Europe are a single large family with varying degrees of
chin and haemophilia :)

------
iguy
There's a much bigger and longer story than this. Roughly speaking, it's my
understanding that the catholic church suppressed this in Europe from roughly
1000 years ago, essentially as a way to counter alternative power centres.

Here's a famous article about Iraq, where this did not happen:

[http://www.theamericanconservative.com/articles/cousin-
marri...](http://www.theamericanconservative.com/articles/cousin-marriage-
conundrum/)

Here's a discussion of a recent paper:

[http://marginalrevolution.com/marginalrevolution/2018/01/mar...](http://marginalrevolution.com/marginalrevolution/2018/01/marrying-
cousin-bad-democracy.html)

~~~
narrator
I think that someone could write a very reasonable sounding evolutionary
psychology article about why the guiding hand of natural selection intervened
and stopped cousin marriage due to higher rates of genetic abnormalities.
However, in this case they'd be wrong in that the Catholic Church intervened
directly and conciously and put a stop to cousin marriage.

Finding out that a phenomenon is not due to evolutionary psychology requires
careful historical research and that's hard work. Making up evolutionary
psychology ideas though takes no time and can make for a great clickbait
article.

~~~
iguy
It seems clear evolution has uniformly negative opinions of brother-sister
couples.

But cousins are more interesting, because the biological downside of having
some ill (or just thick) grandkids must be balanced against the upside of
having a tight clan, without divided allegiances, to fight off other clans.

------
GreeniFi
A friend reported going to the wedding of German first cousins who married.
The groom opened his speech with, "just in case you're still wondering, yes
it's legal".

No, they were not the British royal family.

And apparently it was quite an uncomfortable moment.

I relate the story as something which would have been quite normal once,
whilst legal now, is fairly taboo. I'm not sure why, although obviously feel
and appreciate the taboo.

~~~
JumpCrisscross
> _I 'm not sure why_

Taboo because we discovered heredity. Legal because this isn’t prevalent
enough to merit national attention.

~~~
da_chicken
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/t...](https://www.psychologytoday.com/blog/animals-and-
us/201210/the-problem-incest)).

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.

~~~
alva
"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.

~~~
jrmarc
[http://www.bbc.com/news/uk-england-
leeds-23183102](http://www.bbc.com/news/uk-england-leeds-23183102)

[http://www.dailymail.co.uk/news/article-1392217/Muslim-
outra...](http://www.dailymail.co.uk/news/article-1392217/Muslim-outrage-
professor-Steve-Jones-warns-inbreeding-risks.html)

It's noteworthy that it's simultaneously socially unacceptable to criticize
Pakistanis for their preference for first cousin marriages, despite the
undeniable harm caused by it, and yet it's also socially unacceptable for
whites to have the much less incestuous preference for just marrying other
whites, despite the absence of harm:

[http://www.slate.com/articles/news_and_politics/politics/201...](http://www.slate.com/articles/news_and_politics/politics/2014/04/okcupid_and_race_is_it_racist_to_date_only_people_of_your_own_race.html)

~~~
foldr
The first article you link to is a BBC news article that says exactly what you
claim it is socially unacceptable to say. In the second article, the only
people getting outraged are those who've been referred to as "inbred". You can
hardly expect them to take kindly to that description.

~~~
jrmarc
[https://www.express.co.uk/news/uk/591577/British-
Pakistanis-...](https://www.express.co.uk/news/uk/591577/British-
Pakistanis-13-times-more-disabled-children)

> Baroness Flather said because of 'inbreeding', members of the ethnic group
> are 13 TIMES more likely than the rest of the UK population to have disabled
> children.

> The Pakistan-born peer has called on the Government to take steps against
> the issue of unions between close relatives in Muslim communities, which she
> called an "outdated, un-British custom".

...

> She also accused Britain of a "cowardly reluctance to tackle damaging social
> practices within certain ethnic minorities".

> In what has been described as a brave attempt to break a taboo she said
> _there was a fear of "accusations of racial prejudice" which has made the
> issue "unsayable"._

> She added: "That is certainly what happened over the disgraceful sex-
> grooming scandal in Rotherham, in which the civic authorities, including the
> police and social services, tried to cover up the systematic abuse of more
> than 1,400 vulnerable girls by predatory gangs of Pakistani heritage men."

------
jrmarc
While isolated instances of first cousin marriage aren't especially harmful,
contrary to what some comments here suggest, if done across successive
generations, these unions can produce a catastrophic unmasking of harmful
recessive alleles, and the nations with the highest rates of consanguineous
marriages also often have the highest rates of birth defects (see p. 22):
[https://www.marchofdimes.org/materials/global-report-on-
birt...](https://www.marchofdimes.org/materials/global-report-on-birth-
defects-the-hidden-toll-of-dying-and-disabled-children-full-report.pdf)

However, while the dangers of inbreeding depression are common knowledge, it's
worth pointing out that outbreeding depression exists as well. Where lies the
ideal balance between these two extremes? Surprisingly, it appears to be
marriages between third or fourth cousins, if you use fecundity as a proxy for
general offspring health:
[https://www.sciencedaily.com/releases/2008/02/080207140855.h...](https://www.sciencedaily.com/releases/2008/02/080207140855.htm)

A third or fourth cousin is a person with whom you share first cousin
grandparents or great grandparents--essentially a distant relative, or simply
put, someone of your own "race," which is quite at odds with the "hybrid
vigor" claims often made to tout interracial marriage. Apparently just
marrying any old white person (if you're white) gives you all the hybrid vigor
your offspring need.

------
Retric
I have some doubt that the generations are that cleanly separated when doing
genealogy. The if nothing else the youngest and oldest children of a couple
can be 20+ years apart. The same person could easily show up as someones great
grandparent (3) and their great great grandparent (4).

~~~
ajmurmann
In high school I sometimes hung out with a friend and his uncle. The uncle was
two years younger than us.

~~~
mikestew
I have an aunt that’s two weeks younger than I. Another aunt from that same
mother is only six or seven years older than I. The fact that my Mom got
started young with me is a contributing factor.

------
xchip
TL;DR:

It wasn’t until after 1875 that partners started to become less and less
related.

~~~
Gibbon1
Reminds me of something I read about that in the 1970's.

Mostly people married someone born 10 miles from them. Suddenly steam ships
and railroads came.

------
touringcomplete
It was the invention of the automobile that made it possible to stop marrying
cousins.

