1st cousin marriage

It really is baffling that anybody is arguing against criminalising sex with first cousins and banning marriage to first cousins given the weight of scientific evidence of the harm it causes.

What I find even more disturbing is that those who have tried to argue against doing so on this thread have streadfastly refused to engage with any of the clear reasons why it is necessary to do so and state a coherent counter-argument, or provide any evidence or rational argument whatsoever to support their own position.

There have been horrible insults, insinuations of racism, attempts to discredit or misrepresent science and historic scientists, false equivalences drawn with other unrelated social policy issues which are patently irrelevant to the discussion, insinuations that those saying we should legislate against this are planning to implement forced abortion of babies, attempts to equate decisions about UK law in 2026 to what people did hundreds of years ago before genetic science existed when people had no evidence proving the cause of the disabilities resulting from incestuous behaviours, false claims that the issue can be resolved by “education” when it is evidenced that this has been tried over several decades and not been effective enough to reduce the incidence to anything like acceptable levels (aside from the fact that these attempts to educate frequently resulted in verbal or physical attacks on the healthcare staff doing so), and yet no answer whatsoever to the question of why we shouldn’t legislate against something so harmful to prevent thousands more children being born with incurable and debilitating, horrific medical conditions that are completely avoidable. The question has been asked over and over again and not one poster in support of the status quo has answered it: one has to wonder why.

There is something really wrong with people who think it’s ok for us to let this continue as it is when we have easy ways to reduce the numbers of cases enormously, immediately, by adding a couple of paragraphs to existing laws that exist for precisely the same purpose, now that our scientific knowledge is more advanced and has evidenced beyond doubt the need to do so.

Why are some people arguing against the UK making this illegal, despite such unequivocal evidence supporting the need to legislate to prohibit it? I genuinely do not understand this because despite such posters being asked repeatedly to explain a legitimate basis for their view it is conspicuous that every single poster who has commented in support of the status quo have refused to provide any rational or scientifically valid answer this question.

It is all quite sinister.

The risk of birth defects in the offspring of a one-off cousin relationship, where both parents have no known genetic disorders, is actually about the same as the risk in babies born to mothers aged 35 and older. Nobody is saying having a baby after the age of 34 should be made a criminal offence.

There is absolutely no doubt that repeated cousin marriage, moving down through the generations, is the cause of genetic disorders. It's tragic, and communities which do this culturally should absolutely be educated about it, discouraged in the strongest terms etc.

I do not think sexual relationships or marriage between consenting cousins should be made illegal though. I know a married couple who are first cousins, with two kids (healthy). No family history of cousin marriage, a one-off. They're just ordinary people, living ordinary lives and contributing to society. Why should this scenario be criminalised?

You have been very strident on this thread, making huge long posts which I admit I have not read in full. I'm guessing you're a lawyer. You do appear to have an imperfect understanding of the science yourself, a fact which you're glossing over. See my comment above re. haemophilia, also Charles Darwin much, much earlier in the thread. Kind of like the pot calling the kettle black to accuse someone else of posting unscientific nonsense.

Yes, I agree. Given that we have laws prohibiting the marriage of close family members, and we know the harm involved to children and the financial burden, it is completely consistent to ban marriages of first cousins.

That is not true. These are false statistics that have been bandied about that are thoroughly debunked. Please stop posting unscientific nonsense.

This is a false equivalence. There is a right to bodily autonomy. An embryo doesn’t have rights as it is not yet a legal person until it is born and cannot be considered as a viable individual with its own rights if it cannot exist separately outside its mother’s body with a realistic chance of survival.

This is completely different to a public policy matter regarding whom the state decides to grant rights to marry, which is entirely a matter for legislature because marriage is about state-conferred legal rights/ property etc via state recognition of a relationship. It is, therefore, for the state to make such choices, not individuals, and they should do so within our legal system based on not restricting personal freedoms more than is required to maintain a stable and functioning society and prevent unnecessary harm. In this case scientific evidence shows that marrying a cousin doesn’t meet this test so should not be permissible. Actively prohibiting an action in which the state has no involvement (what women choose to do with their own bodies) is completely different to the state actively endorsing something through state functions, such as conferring legal marital status. I.e. This is the state’s business and realm of decision-making, whereas what a woman chooses to do with her own body is not. There is, therefore, no possible rational argument as to why marriages between cousins should be permitted by the state per the principles of our law, given the scientific evidence.

The case of whether sex between cousins should be classified as incest is more complex because for the reasons above the state generally stays out of personal decisions on relationships however, this comes with the caveat that when something causes proven harm and the harm prevented by the limitation of it is proven to far outweigh any restriction on personal freedoms, the state will step in. It also has to be enforceable.

As a result, the crime of incest exists in law, because the harm this causes both genetically to descendants and to those who are in these (almost always coerced) “relationships” is so high that the curtailment of personal freedoms is necessary in these circumstances, and beneficial to society as a whole, and the sacrifice of personal freedom involved in prohibiting it is minimal given that pretty much nobody in their right mind with freedom to choose would want to do it anyway - it’s almost always abusive. Given the scientific evidence that the harm caused by procreating with cousins (especially over multiple generations) can easily be as significant as that from doing so with parents/ siblings/ aunts/ uncles, and the evidence of many of these “relationships” being coercive, the case for adding cousins to the list of relatives within the definition of incest is clear. There is no significant curtailment of freedom involved: anybody who wishes to can still have children, or marry whomever they like, they just need to pick a partner from the 3 billion adults on Earth of the opposite sex who aren’t a close relative.

Therefore, the balance of rights in this case is a no brainer. It is also easy to prove, easy to enforce robustly, and will actually reduce levels of personal freedom being curtailed overall because fewer people will be coerced into unwanted relationships and for many women it will mean it’s easier to leave abusive relationships, as well as preventing needless harm to children. A clearer “no-brainer” in terms of the balancing of rights and freedoms in determining law could hardly be imagined than the case for legislating against this, given what we now know about genetics.

This is fundamentally different to whether a woman might have a glass of wine during pregnancy. That is a case where education has worked. Far fewer women drink in pregnancy at all now, and those who do drink very small amounts generally, which have not been proved to cause harm in those quantities. In this case we also know that the few who do drink large amounts causing disabilities for children generally do so in an undetectable way (have you seen hammered pregnant women in public?) and there is nobody to report this if this is happening behind closed doors, so making it illegal would be ineffective because there’d be no way to enforce it on the very people who are causing the harm. Also it would be impossible to enforce because there’s no way to prove in many cases that a woman knew she was pregnant, and in some cases women have alcohol problems so making it illegal would actually cause MORE harm to children because it would encourage women not to seek help during pregnancy if they are suffering from alcoholism when this could prevent further harm to their unborn babies.

We know that the education campaign on this issue has worked for the vast, vast majority of pregnant women. There isn’t a resistance in certain population who are citing that drinking bottles of vodka while pregnant is their absolute right and tradition and that people are being prejudiced by telling them not to do so and claiming that the doctors are making up the evidence that it is bad and that the reason that babies of alcoholic mothers are both with disabilities is because the doctors poisoned them with medicine, is there? Yet these were the views expressed in the documentary that I posted the link to regarding the effects on the children of cousins in Bradford: the parents were in denial and some claimed the doctors were responsible for their children being disabled, and the medicine the doctors had provided was the cause!

Again, the outcomes and overall consequences of legislating need to be considered. In the case of sex with/ marriage to cousins, legislating against this actually strengthens women’s ability to seek help or leave what are often abusive and controlling situations: it’s much easiler to prove someone is your cousin than to prove they raped/ coerced/ abused you etc. Prosecutions would act as a deterrent from people engaging in the behaviour in the first place. The ability of women to leave and get help in refuges/ from police is raised. The practice will be reduced by criminalisation and rates will fall sharply and many children will be saved from being born into miserable and painful, short lives with debilitatating and untreatable conditions.

I checked Sweden the marriage isn't legal but the act between two cousins is

I don't see how this can be prevented, You can make marriage illegal, but not reproduction. Nearly half of British babies are born to unmarried parents. While this may be less common in the close communities where cousin marriage is more common, they could choose to have religious marriages without official state recognition.

In any case, a single cousin marriage isn't more risky than many other things that are not illegal, like advaned maternal age or drinking alcohol while pregnant. What is really risky is multiple generations of cousin marriages.

I don't see how this can be prevented, You can make marriage illegal, but not reproduction. Nearly half of British babies are born to unmarried parents. While this may be less common in the close communities where cousin marriage is more common, they could choose to have religious marriages without official state recognition.

In any case, a single cousin marriage isn't more risky than many other things that are not illegal, like advaned maternal age or drinking alcohol while pregnant. What is really risky is multiple generations of cousin marriages.

You are right. If Albert had also carried the gene, he would have had haemophilia himself (males cannot be asymptomatic carriers) and it is known that he didn'rt.

Not in the case of hemophilia, because it's sex-linked. The gene which causes haemophilia is carried on the X chromosome. Queen Victoria was a carrier, and she passed it onto Leopold via the X chromosome. Leopold, being male, inherited his X chromosome from Victoria, and his Y from Albert. The Y chromosome has no gene (normal or faulty) to counteract the one carried on the X chromosome, so Leopold expressed the disease. It was nothing to do with Albert.

Rape and murder were a false equivalence.

With both multi-generational 1st cousin marriage and drinking we're talking about public health. The state regulates all sorts of drugs, alcohol is no different, we just don't regulate it (much), though other countries do. It's a public health issue, both for the individual drinking, fetuses they may be carrying, and others who are harmed by alcohol abuse (violent and sexual crime crime is strongly linked to alcohol abuse).

No: it would only manifest in the child if they received this gene from both parents, which is far, far more likely if they are related to each other than if she’d had children with someone unrelated. Children receive two copies of each gene, one from each parent. If one of the parents passes on a defective gene but they get a normal copy of that gene from the other one, then they are fine. It is when they receive a defective copy of the gene from BOTH parents that the genetic disorder manifests, rather than them just being a carrier of it.

That’s the entire point, and why inbreeding leads to a compounding risk of significant genetic defects, as has been explained in the thread multiple times now.

The chances of someone unrelated to you having the same genetic defect as you are often incredibly rare: in some cases 1/1,000,000 or even 1/1,000,000,000. If you marry a relative who is a carrier of the same genetic defect that you carry (far, far more likely, obviously!) then the chances of your child inheriting defective copies from BOTH parents and therefore being disabled by it because they have no healthy copy of the gene rise to 1/8.

This is a false equivalence. There is a right to bodily autonomy. An embryo doesn’t have rights as it is not yet a legal person until it is born and cannot be considered as a viable individual with its own rights if it cannot exist separately outside its mother’s body with a realistic chance of survival.

This is completely different to a public policy matter regarding whom the state decides to grant rights to marry, which is entirely a matter for legislature because marriage is about state-conferred legal rights/ property etc via state recognition of a relationship. It is, therefore, for the state to make such choices, not individuals, and they should do so within our legal system based on not restricting personal freedoms more than is required to maintain a stable and functioning society and prevent unnecessary harm. In this case scientific evidence shows that marrying a cousin doesn’t meet this test so should not be permissible. Actively prohibiting an action in which the state has no involvement (what women choose to do with their own bodies) is completely different to the state actively endorsing something through state functions, such as conferring legal marital status. I.e. This is the state’s business and realm of decision-making, whereas what a woman chooses to do with her own body is not. There is, therefore, no possible rational argument as to why marriages between cousins should be permitted by the state per the principles of our law, given the scientific evidence.

The case of whether sex between cousins should be classified as incest is more complex because for the reasons above the state generally stays out of personal decisions on relationships however, this comes with the caveat that when something causes proven harm and the harm prevented by the limitation of it is proven to far outweigh any restriction on personal freedoms, the state will step in. It also has to be enforceable.

As a result, the crime of incest exists in law, because the harm this causes both genetically to descendants and to those who are in these (almost always coerced) “relationships” is so high that the curtailment of personal freedoms is necessary in these circumstances, and beneficial to society as a whole, and the sacrifice of personal freedom involved in prohibiting it is minimal given that pretty much nobody in their right mind with freedom to choose would want to do it anyway - it’s almost always abusive. Given the scientific evidence that the harm caused by procreating with cousins (especially over multiple generations) can easily be as significant as that from doing so with parents/ siblings/ aunts/ uncles, and the evidence of many of these “relationships” being coercive, the case for adding cousins to the list of relatives within the definition of incest is clear. There is no significant curtailment of freedom involved: anybody who wishes to can still have children, or marry whomever they like, they just need to pick a partner from the 3 billion adults on Earth of the opposite sex who aren’t a close relative.

Therefore, the balance of rights in this case is a no brainer. It is also easy to prove, easy to enforce robustly, and will actually reduce levels of personal freedom being curtailed overall because fewer people will be coerced into unwanted relationships and for many women it will mean it’s easier to leave abusive relationships, as well as preventing needless harm to children. A clearer “no-brainer” in terms of the balancing of rights and freedoms in determining law could hardly be imagined than the case for legislating against this, given what we now know about genetics.

This is fundamentally different to whether a woman might have a glass of wine during pregnancy. That is a case where education has worked. Far fewer women drink in pregnancy at all now, and those who do drink very small amounts generally, which have not been proved to cause harm in those quantities. In this case we also know that the few who do drink large amounts causing disabilities for children generally do so in an undetectable way (have you seen hammered pregnant women in public?) and there is nobody to report this if this is happening behind closed doors, so making it illegal would be ineffective because there’d be no way to enforce it on the very people who are causing the harm. Also it would be impossible to enforce because there’s no way to prove in many cases that a woman knew she was pregnant, and in some cases women have alcohol problems so making it illegal would actually cause MORE harm to children because it would encourage women not to seek help during pregnancy if they are suffering from alcoholism when this could prevent further harm to their unborn babies.

We know that the education campaign on this issue has worked for the vast, vast majority of pregnant women. There isn’t a resistance in certain population who are citing that drinking bottles of vodka while pregnant is their absolute right and tradition and that people are being prejudiced by telling them not to do so and claiming that the doctors are making up the evidence that it is bad and that the reason that babies of alcoholic mothers are both with disabilities is because the doctors poisoned them with medicine, is there? Yet these were the views expressed in the documentary that I posted the link to regarding the effects on the children of cousins in Bradford: the parents were in denial and some claimed the doctors were responsible for their children being disabled, and the medicine the doctors had provided was the cause!

Again, the outcomes and overall consequences of legislating need to be considered. In the case of sex with/ marriage to cousins, legislating against this actually strengthens women’s ability to seek help or leave what are often abusive and controlling situations: it’s much easiler to prove someone is your cousin than to prove they raped/ coerced/ abused you etc. Prosecutions would act as a deterrent from people engaging in the behaviour in the first place. The ability of women to leave and get help in refuges/ from police is raised. The practice will be reduced by criminalisation and rates will fall sharply and many children will be saved from being born into miserable and painful, short lives with debilitatating and untreatable conditions.

A community intermarrying in a small gene pool is the issue. 1st cousin marriages are obviously a part of that, but if you stop that and everyone just marries 2nd cousins instead, you don’t really improve the situation. And if by focusing on criminalizing the practice you drive the community to become more insular and decrease the number of people who marry outside the community you make it worse.

Apologies - I have links turned off.

Messaging takes time to sink in and become trusted (and sometimes it's just very clumsily done). One way or another the message has been getting through, though, because understanding about the risks of 1st cousin marriage has been increasing in younger generations.

I posted this early in the thread, and another poster posted it again later. Thanks for higlighting it again. But it having been posted at least three times now there are still posters who refuse to accept reality and scientific fact, much like the parents featured in the documentary. This is why the law needs to be changed to enforce change: there are certain people who will not change their behaviour out of choice, despite the overwhelming evidence of the harm they are causing.

Anyone who isn't opposed to it - please the aforementioned link to 'when cousins marry'.

Edited to remove link which had already been posted.

This is true, however it seems to have been a spontaneous anomaly in Victoria herself, there was no haemophilia in the family before her, which would have been an issue whoever she married, he could have been a native American, she would have still passed it on. There is speculation that it was came via her father who was getting on a bit by the time she was conceived