When did marrying a cousin become socially unacceptable?

[LionBird]

I'm a big Agatha Christie fan and noticed there are quite a few references to cousins being in a relationship. I'm rereading Taken at the Flood currently, which is set in 1946, and the main character is engaged to her cousin and nobody seems to think it's strange! Obviously it was quite common in royal circles too in the 19th century but post-WW2 isn't that long ago so I'm not sure how and when it became unacceptable to have a relationship with a cousin - can anyone shed some light on this?

Presumably, once it became known that marrying a first cousin can considerably increase the likelihood of inherited disabilities or other health conditions.

Though even before DNA evidence, I think it was fairly well known that ‘inbreeding’ was not a good thing.

My cousin married a cousin - not first cousins though.
they have 2 amazing & healthy adult kids.

My grandparents were first cousins. As far as we're aware, we're all OK health wise but it did make me wary as I got older and had my own kids

Consanguinity (married between cousins) has been banned by the (Catholic) Church since pre-medieval times. Historically, royal families and the aristocracy had to seek a papal dispensation to marry someone, if they were more closely related than second cousins.

Yes - the Catholic Church definitely forbade it from early Middle Ages afaik .
It was considered Incestous .

It's only really in the last century or so that infant mortality in rich countries has plummeted. Incidence of all sorts of serious health problems has fallen. Life expectancy is very high now. Until two or three generations ago there was a high chance of dying in a war or an accident if you were male and in childbirth if you were female. In those circumstances the chance of having a child with a disability or serious health condition was already so high that passing on a heritable condition possibly didn't seem so bad. Lack of welfare support would also have made it a priority to keep money in the family.

In ‘Jude the Obscure,’ Sue says ‘it is bad for cousins to marry’ - published 1895.

My grandmother married her cousin. Can't really remember anyone commenting on how strange it was. It was a second marriage though, after she had had children.

I do remember my mum commenting on the weirdness that she said he had never seen her naked after more than 20 years of marriage.

There were both odd though

it is a very common question in clinical genetics

I remember reading a Tracy Chevalier book where the research she had done for the story showed very unhealthy practises in some Swiss villages in the 1800’s; fathers would impregnate their daughters with their first child. It was so common it was duly noted in the church books.

I do know some people whose parents are first cousins. But I think thst has been outlawed now, due to the health challenges.

It still happens but because it’s not socially acceptable you don’t hear about it.

My good friend is married to her first cousin, they have children. 99% of people who know them don’t know that they are cousins…… just their family and childhood friends know.

Yes, my dad (surgeon) operated on a child whose parents were cousins. He didn't have any contact with the parents, but his colleague gently advised them that they needed to be careful having any more children. The dad said it was OK and that he was going to get together with another womam so they could have children - his cousin on the other side! This was maybe ten years ago, no the 40s. But the family was from a culture where marrying cousins was still common

Re the Catholic church keeping records of close relationships, are similar records kept of sperm donors, egg donors etc? How awful to accidentally marry a sibling. Hopefully this has been considered.

My cousins feel like siblings to me. I just couldn’t even imagine feeling attracted to one of them.

Knowledge of genetics. Charles Darwin married his cousin Emma Wedgewood

It's an election issue - certain cultures still favour cousin marriages. Political parties won't risk losing those communities votes. But, yes, it should absolutely be illegal.

They had hæmophilia because Victoria's father was 51 when she was born after the scramble to produce a legitimate child after the death of Princess Charlotte in childbirth.

The only cousins I know who married had only one child who died due to genetic issues, they then decided not to risk having anymore. They are of the older generation though where it wasn’t so frowned upon. I suppose we as a society now know that it isn’t a good idea, the science speaks for itself, and when you know better, you do better.

It hasn't, unfortunately. Radio 4 series The Gift has featured many unintended consequences of DNA testing on Ancestry etc including unexpected relationships.

My husbands grandparents were cousins - they married in the forties. I must admit I was surprised when I learnt this and found it a bit icky. All three of their children have had health issues but not sure if it's due to cousin marriage or poor health due to life style.

@Gasp0deTheW0nderD0g Oh dear!

This just isn't accurate. Haemophilia is common historically across the royal families of Europe - look at the Romanovs. Why? Because they're all inbred! Haemophilia is genetic, not age-determined (unlike something like Downs Syndrome).

That proves nothing though, much bigger numbers are needed to make meaningful statements. The fact is that cousin marriage is known* *to iincrease the risk of genetic/medical conditions.
It's like saying 'my granny smoked and didn't get cancer so smoking doesn't cause cancer'.

I used to volunteer at a school for special needs children. The amount of children with genetic issues, where the parents were related, was astounding. Consanguineous marriage is much higher in some communities.

2 families at the school were not only related, but all 4 parents were too. It was unclear if the parents were all cousins, or potentially more closely related! Between them, they had 7 children that survived to get to school age- all with profound disabilities. When I left there, 1 mother was pregnant yet again.

The children having Down's may very well be as a result of their parents' consanguinous marriage; but if they're very religious as you describe, they would also be highly unlikely to consider an abortion as an option when they discovered that they were going to have a child with Down's, unlike a very large proportion of non-religious folk.