It has long been known that incest is not as bad as you think. Anti-cousin marriage laws are like prohibition laws and blue laws. They arise from a Christian conservative movement that swept Western Civilization from the late 18th century through the 19th century, up to about the time of the repeal of Prohibition.
Sure, marrying, or just plain having sex with, your sibling is disgusting. I mean, think about it. No, wait, don't even think about it. But cousin marriage? That depends. Your cousin may be kinda cute, you never know.
But seriously, anthropologists have long known of ... and have had two distinctly different explanations for ... patterns of marriage that involve linking up various kinds of cousins. At this point, let's just say that cousin marriage tends to benefit ... in terms of coalition formation, power management, and with respect to inclusive fitness .... the ascending (older, in charge) generation, even if it is no necessarily ideal for the marrying generation. This may well explain the pattern that we see: Prescribed cousin marriage is common in many scieties, but the degree to which it happens is at least somewhat correlated, it would seem, with he level of patriarchy. The more control older typically male power brokers have over things, the more people stick with cousin marriage. The less such power, the more rule breaking we see.
Forbidding laws are foreboding things. If you make a law that says that some behavior should never, ever happen, then people may become more fearful of the outcome of such actions. Cousin marriage laws instituted mainly during the last half of the 19th century have led to the general understanding that if cousin have a baby, it will have two heads. But in fact, and this has been known scientifically for decades, the increased rate of revelation of hidden recessive mutations in marrying cousins is small. It is about the same as a woman over 35 or so having a child.
A paper just out in PLoS Biology reviews the history of cousin marriage, its prohibition and the related controersy, in the West.
The conclusion is the following interesting conundrum:
...we note that laws barring cousin marriage use coercive means to achieve a public purpose and thus would seem to qualify as eugenics even by the most restrictive of definitions. That they were a form of eugenics would once have been taken for granted. Thus J.B.S. Haldane argued that discouraging or prohibiting cousin marriage would appreciably reduce the incidence of a number of serious recessive conditions, and he explicitly characterized measures to do so as acceptable forms of eugenics .... But Haldane wrote before eugenics itself became stigmatized. Today, the term is generally reserved for practices we intend to disparage. That laws against cousin marriage are generally approved when they are thought about at all helps explain why they are seemingly exempt from that derogatory label.
It is obviously illogical to condemn eugenics and at the same time favor laws that prevent cousins from marrying. ...
Interesting, that link between religious belief and eugenics.
As a paper published in an Open Access journal, you can review it yourself. Do read this paper, it is well done and quite accessible.
Diane B. Paul, Hamish G. Spencer (2008). "It's Ok, We're Not Cousins by Blood": The Cousin Marriage Controversy in Historical Perspective PLoS Biology, 6 (12) DOI: 10.1371/journal.pbio.0060320
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But what about Deliverance?
In my genealogical research, I have found four instances of 1st cousin marriages dating from the mid-18th century (my 4th great grandparents in Middleborough, MA) to the early 20th century in Michigan. I'm not making any particular point, just the observation that it seems cousin marriage was/is more common than I thought. No information about any deleterious effects has shown up in my family research.
Just speculating here - sure, cousin marriage isn't that big a deal - at first. But what if you continue the practice, generation after generation? Aren't you continually increasing the risk of problems? Perhaps it is wise to discourage the practice so that it doesn't become a family tradition, of sorts?
cephyn: actually, at some point you decrese risk because you eventually expose many of the deleterious traits.
BTW, strict cousin marriage works best, genetically, in societies where there it is cross cousin marriage, there is a certain amount of paternity mis attribution and pretty strict male philopatry. In this way one's cousin is often more distantly related and it is difficult to accidently marry your full sibling.
Up to a point. I'm an Askenazic Jew. We are a population with many different recessive allele linked diseases. Cousin marriages for us are particularly bad.
In general, there is a statistical increase in the likelyhood of disease among cousin marriages. The question then becomes really what increase would be severe enough to justify imposing on our personal liberties to protect the eventual offspring. I suspect many people for example would be willling to prohibit marriages between two people both of whom were carriers for Tay-Sachs. The line here isn't that clear. We risk engaging in the genetic fallacy by linking our modern day policy decisions to the exact background of where laws came from.
I'm not an expert in this area, but I've heard the terms "in-cousin" and "out-cousin" used to describe the possibilities.
If a male marries his _father's_ sibling's daughter, then the marriage is within a single patriarchal lineage and doesn't serve much purpose. But if a male marries his _mother's_ sibling's daughter, that reinforces an alliance between two patriarchal lineages and is thus politically useful. The bond between the two houses formed by the father-mother marriage is extended to a new generation by the out-cousin marriage.
It's my amateur's understanding that plenty of cultures have stressed this in-cousin vs. out-cousin distinction, with the "correct" type of cousin marriage encouraged for members of royalty or similar powerful elites. So, for Greg, are "cross cousin" and "out-cousin" synonyms?
The father's sibling's daughter is not automatically of the same patriline. If the father's sibling is a female, then her offspring are the cross cousin, and they are of a different patriline assuming she married a man not of her patrilne (Which, in a cross cousin system is required).
You have to think about cross cousin vs. parallel cousin, not in-cousin vs. out-cousin. Those terms are inaccurate and often used incorrectly.
A cross cousin is where cross gender. Father's Sisters offspring or Mother's Brother's offspring. Father's Brother's offspring and Mother's Sister's offspring are your parallel cousins.
There are cultures that practice both, but more commonly, and more sensibly, is cross cousin prescribed marriage. Like Darwin and His wife, for instance.
I can count the number of cousin marriages in my family on the fingers of one hand. About seven, I think.
I sure hope the "Eww" Factor constitutes enough social pressure to keep the practice at a minimum.
Outbreeding is the 21st Century way, man. We have 6 billion people on this earth, surely there's one out there for each of us (who choose the "married lifestyle") who isn't consanguinous?
@Hal in Howell, ever seen the 4th season X-Files episode titled "Home"?
Cousin marriage is illegal in the US?
Are there any other countries where this is also so? I'm not aware of any, and my google searching has brought forth a few claims that this prohibition is unique to the US.
It is illegal in the US in manyh states, but not always in those states where it is illegal. It is allowed in much of Appalachia, alaska Texas, places like that. I think it is illegal in very few places outside the US.
Wait, what?
More seriously, it is legal to marry your first cousin in these states:
Alabama
Alaska
California
Colorado
Connecticut
District of Columbia
Florida
Georgia
Hawaii
Maryland
Massachusetts
New Jersey
New Mexico
New York
North Carolina (not double first cousins)
Rhode Island
South Carolina
Tennessee
Vermont
Virginia
And in Arizona, Illinois, Indiana, Maine, Utah, and Wisconsin they can marry if they can't have children.
ps - Generally speaking, if you come from a state where the marriage is legal, and move to one of the (minority, note) states where it isn't, your marriage is still valid. 'Cause at least you're not gay.
"It has long been known that incest is not as bad as you think. "
Dude, you haven't met my relatives.
*shudder*
I would remind everyone that Charles Darwin married his first cousin and had 10 children by her.
Am I really the only person who doesn't have this visceral reaction?
The Catholic church of the early Middle Ages apparently prohibited marriages between fifth cousins or nearer though dispensations could be gotten (admittedly finding out you were within the prohibited degree when you wanted to get out of a marriage was a quick way of getting an annulment (and for royalty or nobles finding someone who was noble and not within the prohibited degree became quite tricky).
Oddly enough, given this, the Bible has a fair number of cousin marriages. It practically requires it for women who have no brothers (in such a case they inherit their father's property but have to marry back into his family so the family doesn't lose the property). Abraham married his half-sister Sarah. Isaac marries his cousin's daughter. Jacob marries two of his cross cousins.
But cousin marriage? That depends. Your cousin may be kinda cute, you never know.
I got some very cute cousins. And that is all I'm saying. ;)
I would remind everyone that Charles Darwin married his first cousin and had 10 children by her.
Einstein and Bach also married their first cousins. In Bach's case they had several children together, some of whom turned out to be very good musicians.
The laws are about discouraging something that's bad if it was done a lot, like every generation. Then how about spitting. If we all spat all the time, then city-living would be horrible. Thus, no one should be allowed to do it?
In India one would find different forms of consanguineous marriage, this is of course tied to patriarchy and the caste structure of the society. The closest-relation would be uncle -niece, a man can marry his sister's daughter but not his brother's daughter. As the sister has married out. Studies show mixed results about increased genetic vulnerability, tends more towards 50% chance of risk for genetic disease in consanguineous marriage...... same as non-consanguineous ?
Although never spoken aloud inside these homes, incest is rampant but sibling incest maybe rare.
>>Am I really the only person who doesn't have this visceral reaction?
No, I don't, unless we think humans are somehow very different from rest of the animal kingdom.
Of course it's a eugenic law. I don't see what's wrong with that in itself. The word "eugenic" just means good birth, and we have many eugenic laws - e.g. we don't let people just run off and use Thalidomide whenever they want to. We take it that the state has an interest in the birth of healthy children.
The question is, "Is it a good, rationale, humane eugenic law or is it a bad, dumb, cruel eugenic law, or is it something in between?" I actually think that it's closer to the bad, dumb, cruel end of the spectrum.
My great-grandparents on my mother's side were first cousins and they were married in Missouri. (Illegals?)
Although I might describe certain members of my family as daffy, none of them seem any stranger than the average person.
cephyn:
This quote demonstrates that people don't realize that cousin reproduction does not, per se, increase the frequency of mutated genes. Indeed, if the genes are harmful to fertility it will reduce their frequency after the cousins' children's generation.
If they have children with non-cousins then their mutated genes are just are likely to be inherited as if they have children with cousins. The only difference is that recessive genes are more likely to come together in the generation produced by the cousins. You could say that recessive genes will probably come together sooner or later, cousin reproduction just makes it sooner.
"Oddly enough, given this, the Bible has a fair number of cousin marriages. "
That is because the OT is the story of a patrilineal society with prescribed cross cousin marriage. A famous anthropology kinship term comes from the bible, for instance. The Levirate is the taking of a wife by a man from his deceased brother, for instance.
Chris: Right. There are many many potentially harmful recessive alleles, and the vast majority of them are so rare we don't even know they exist (we guess). And, these alleles will never be expressed (oversimplified, but a valid model for these purposes) because they are distributed thinly and widely in the population.
But identical twins having kids would likely expose many of them over a few offspring for obvious reasons.
The chances of this is much much lower with 1/8 cousins, of course, but that is the point
(But of course, the point of the paper at hand is that the actual increase of risk is small)
Ironically, although cousin marriage is legal in many states, it is illegal in some of the places that get the most jokes about inbreeding in the US: for instance, Arkansas, Maine and West Virginia that are frequently the butt of inbreeding jokes (unfairly) all ban or restrict first cousin marriage, whereas Massachusetts or New York do not.
I suspect some of the motivation to keep these laws in place is fear of ridicule if they are lifted in places that are already the butt of jokes, though I have no proof of this.
Ahem,Greg,
can I quote your post to some of my female cousins? *cough*
I'm not sure I follow.
Greg said:
"But identical twins having kids would likely expose many of them over a few offspring for obvious reasons."
There is one even more obvious reason why identical twins shouldn't have kids together.
;p
Sigmund,
yup.
On another note, just at the end of the semester in Biology, we were discussing the founder effect, and Doc asked the class how many people had ever known anyone with vanCreveld Syndrome. He was surprised for a moment when I answered that I knew one.
Turns out I was born in raised just outside Philly.
The frequency of vanCreveld Syndrome is about 1 in 60,000 births in the U.S. at large, but in Lancaster County, PA, not far from my home, the frequency is about 1 in 200 births. It's 300x more common there than anywhere else.
Why?
Lancaster County, PA is Pennsylvania Dutch country, a tightly knit Amish community founded by just 20 people. One of those people, either Samuel King or his wife, was heterozygous for vanCreveld's, and because of the insular nature of the community, the trait spread quickly through the population. (vanCreveld's is autosomal recessive and is marked by dwarfism and polydactyly, among other things.)
When I was just a wee one, maybe 7 or 8 years old, a family moved in down the street. They had a very cute little girl about my age that I began hanging out with. She was very good at marbles, though I don't know if that was because of her extra fingers or not.
I just thought it was cool that a girl liked to play marbles.
I hadn't thought about her in years until Doc brought it up.
In a study of Icelandic genealogies third cousin marriages turned out to have the largest number of offspring on average. First or second cousin marriages had lower family sizes, as did marriages between less-closely related pairs.
Of course, Iceland is a small isolated population, so everyone is pretty much related to some degree in the last thousand years. But it makes a great human genetics lab because so much genealogy is documented.
This whole discussion reminds me of a Bill Hicks routine:
"He said, 'I'd like you to meet my wife and sister.' And there was one girl there with him. Not a thumb between 'em."
I miss Hicks.
For an interesting take on the evolutionary origins of this, see Primeval Kinship : How Pair-Bonding Gave Birth to Human Society (http://www.hup.harvard.edu/catalog/CHAPRI.html)
I've got to admit, as a teen and into my 20s I had the hots for my cousin who was father's older sister's daughter.
Not that I went to family reunions to pick up chicks or anything.
"But in fact, and this has been known scientifically for decades, the increased rate of revelation of hidden recessive mutations in marrying cousins is small. It is about the same as a woman over 35 or so having a child."
I just want to make sure I understand this correctly. The chance of having "something bad" happen in the development of the child in 1st cousin marriage is equated to the chance of a woman over 35 being able to give birth? Or that a woman over 35 that gives birth will have "something bad" happen in the development of her child?
You're not, Azkyroth. I don't get that reaction, either. I won't marry a cousin, but then again, I don't want to get married, period, and I don't have any attractive cousins, anyway!
Given the generally accepted definitions of third base (suffice it to say, they are non-procreative), the title of this post suggests that our host dwells in a particularly, um, advanced milieu.
I can't help but wonder what's going on when, by his own standards, he slides into home...
MPL -
Let me preface my response by admitting that I have done little academically sound research into this topic, but I did spend some time on it.
Those states didn't implement those laws out of fear of ridicule and it's not even all that ironic that they have them.
Arkansas, Maine and West Virginia all share a common trait (though they are far from alone in this), they all had fairly large numbers of degenerate communities. And it's not surprising that they would, as they were some of the earliest settled states. All of these states have mountainous regions that made it easy for small communities to be effectively cut off from the rest of civilization, sharply limiting the gene pool that was generally fairly limited to begin with.
What I find fascinating, is that there are degenerate communities that remained isolated, well into the twentieth century. Some of the oldest had upwards of three hundred years of inbreeding to account for - though most of the oldest died out. And these are also communities that had relatively small generational gaps, because they tended towards shorter lifespans, coupled with a need for able bodies to support the community.
Right or wrong, I suspect that the laws in these states were a response to dealing with the problems inherent to these limited gene pools. And I suspect that there is probably some validity to this. While in the general population, first cousins will have only a slightly elevated risk of defects, if the first cousins are the result of a gene pool that was populated by only a few different families, stretching back fifteen generations, the risk is likely to be significantly higher.
But I will reiterate, I am not well versed in genetics and could be completely mistaken. But even if I am, I'm probably not the first person to make such a mistake and come up with this thread of logic. I know that at least in Maine, this exact thinking seems to have been at least part of the motivation for the law.
Now wait one holy minute, the christian god-idea decides if a baby-soul is going to have genetic problems or not, not the relatedness of the babies parents. Christian god-idea, have mercy on those who are trying to disrupt your wonderful two-headed beasties.
I'll say a brayer for all of you.
I do not think this can be right. Your second cousin is your first cousin's child, so (presumably) your fifth cousin would be your first cousin's great-great grandchild. Why would there be a rule prohibiting marriage between people four generations apart? It is hardly an issue likely to arise very often (and even less often in the middle ages than now, surely).
***
Anyway, so far as I can see, the hangup about cousin marriage seems to be a purely American (and, indeed, American conservative) thing, like creationism. If it has any purchase elsewhere then, also like creationism, that is merely because of the power of American cultural influence.
Of course incest taboos on sexual relations between closer family members are a quite different matter, and may even have a biological basis quite apart from what anyone may know about recessive genes. I do not know where to locate it, but I seem to remember reading long ago that children of the opposite sex, but unrelated to one another, who had been raised communally on Israeli kibbutzim from an early age, more or less as if they were brothers and sisters, were very rarely sexually attracted to one another when they came of age, even though it was in no way prohibited.
That's not correct.
You're thinking of the Westermarck effect
The Catholic Encyclopedia article on consanguinity says that it is "a diriment impediment of marriage as far as the fourth degree of kinship inclusive."
The article does state that prohibitions up to the seventh degree were called for, but also says that the method of computing degrees of relatedness changed, and which degrees were in fact prohibited changed as well.
I am too lazy to read through the whole thing to figure out exactly what and how and when, especially since it looks like they are not entirely certain themselves.
Hm. There's a table at the bottom of the article, but I am not sure how to read it. It also appears to include widows and widowers not being allowed to marry blood-relatives of their deceased spouses, which makes no sense to me anyhow, given that the bible explicitly endorses Levirate marriages, etc.
Razib at Gene Expression has a different view of this and it turns out it's not so simple as you describe it.
http://scienceblogs.com/gnxp/2008/12/cousin_marriage_should_not_be.php#…
Shawn: My quick reading of Razib's post is that we have no disagreements. Also, it turns out that I don't describe it at all. I make a comment or two and point you to the paper, which you can read in all its glorious complexity because it is an Open Access item!
Well, OK. I thought I had the distinction between second cousins and cousins once removed sorted out in my mind, but apparently not. I am still very skeptical of Erp's claim, though. Even if they are of the same generation as you, your fifth cousin is still a very distant relative, and I doubt whether anyone in the early middle ages, apart (perhaps, but record keeping even at those levels was not too good back then) from royalty and upper level aristocracy, would have had any way of knowing whether someone was their fifth cousin or not. Furthermore, within the relatively small communities that prevailed then, this 'rule' would probably rule out marriage between virtually any two people who were likely to ever meet one another (especially as, in practice, you probably would be restricted to marrying within your own social class). Also, cousin marriage was common among the European aristocracy and upper classes (and I woul d guess other classes too) in more recent times, and as Erp him/herself says, it is accepted in the Bible (not to mention being pretty much prescribed in many non-European cultures).
Darn, I didn't see that before making my last post. All the same, could there ever have actually been any enforcement, or even serious or widespread attempt at enforcement, of this in practice? I have no idea who might be my fifth or fourth or even third cousin. If I really wanted to know I could probably find out, given that modern record keeping in first world countries is quite good. But in the early middle ages, when virtually everyone apart from monks (even most parish priests) was illiterate?
Nigel: A couple of points ... in societies where these things emerge as important, there also emerge experts who can figure this all out for you so you don't screw up. I assume all those nice church records that hobbiest genealogists consult these days are there for a reason (probably a few reasons). Also, many societies. Also, many societies handle this, in part, by having a rule that you must always marry out of your patriline and other rules such as cross cousin marriage. Indeed, one of the main functions of the various very complex human kinship systems we see around the world (many of which would utterly confuse and overwhelm the average Westerner) is to manage these sorts of things using methods that work most of the time.
Actually, you may have another problem than show up harmful recessives when marrying your siblings : you tend to have a lower diversity in you HLAs. Especially if it becomes common practice in your family.
That has a number of repercursions, the first of which is a lower efficacy of the immune function (lower HLA diversity means lower antibody diversity). Another is the possible appearance of infectious cancers within that homogenous population, ie cancers that can transmit and thrive from one individual to another (research the tasmanian devil facial tumor for that one).
by not condoning cousin marriages arent religious organizations accepting evolution?
"Am I really the only person who doesn't have this visceral reaction?"
I doubt you are the only one, but most people when bought up with siblings do not feel much sexual attraction for them, nature's way of discouraging too much inbreeding. It also probably depends on your sibling - mine was some years older than me and used to beat me up. Either way I felt absolutely no sexual attraction.
I'm not attracted to mine either, but I don't find that couple in Germany disturbing in the slightest, for instance.
I certainly understand people having a visceral reaction to sibling or parental incest, I used to myself. But several years ago I rather changed my perspective after reading (of all things) a pornographic story. I had bought a discount three pack of magazines, which if you've ever bought one you know that the one slipped into the middle, is usually something bizarre that doesn't sell much.
This one was a extreme fetish magazine. Having a rather extreme interest in psychology and an especial interest in human sexuality, I found it to be a treasure trove of information. Explaining fetishes from diapers, to latex and feces (together) with a great deal in between. Included was a section called All in the Family.
One story that stuck out, was written by a women who talked about losing her virginity to her brother, because she had been very nervous about it. She talked about the close, platonic relationship she had with her brother and how he was so very considerate of her needs while she had sex for the first time. And thinking about it, I realized that hers was probably much better than the firsts of many women I knew, who fumbled around with some boy who was either just as nervous as they were and/or completely inconsiderate about it. I also considered that most women I knew didn't have any kind of relationship with the person they lost their virginity to, while this women had a warm and caring relationship with the person she lost hers to.
While it was definitely not something that I could see myself being interested in, I certainly can understand the attraction of learning about sexuality with someone that one cares about outside of romantic or purely sexual contexts. It definitely makes me disinclined to find the German couple that Azkyroth mentioned disturbing in the least. Over the years I have run across some extremely bizarre fetishes and realized that there really are things that are rather more disturbing than two people who care about each other having sex or even choosing to spend their lives together.
For that matter, I tend to think that my own fetishes are rather vanilla, yet I know people who find them repulsive, extreme and/or disturbing. Me, I figure whatever floats your boat, unless it is exploitative of the unwilling or those incapable of adult consent. Who the hell am I to judge?
Meh. Not really disgusting, just completely unattractive. I find none of their personalities life partner material. While I don't mind if two adult siblings fall in love and marry, I do find it quite worrisome if they haven't spent a singificantly large amount of time apart prior to that (too unlikely they get together out of habit and fear of the rest of the world, instead of because they work awesomely together as a couple), as well as if they try to have biological children together (as opposed to adopted, or using only one of the two parties' genes mixed with someone outside of the relationship for each kid).
i know that this is several months behind the conversation but if anyone is intereted the risks of a defect between two unrelated people under the age of 35 is 2 to 4%, the risk for first cousin couples the risk of a birth defect is 4 to 6%