Royal Inbreeding

How bad was inbreeding among European royals throughout history? I know we’ve discussed this before but I have a few questions. Were there any mental or physical defects that occured from inbreeding? How was everybody related? So many questions!

Haemophilia is a good example of an inherited defect that passed through the Royal families of Europe.

The Hapsburgs (or Habsburgs) of Spain and Austria were well-known for inbreeding. One of the physical defects that happened to later Hapsburgs was the Hapsburg Lip. Carlos II of Spain and Ferdinand I of Austria, both of whom were Hapsburgs, had serious mental problems that may have had something to do with inbreeding.

If you’re interested in this subject, you would probably like the books Royal Babylon by Karl Shaw and A Treasury of Royal Scandals by Michael Farquhar. Royal Babylon has a very entertaining chapter about royal inbreeding.

Szlater Queen Victoria’s passing on haemophillia to her descendents and their married decendents children is not in-breeding.
It just shows that the “Royal Disease” came from a common source.

You state your self it is an “inherited defect”, not an inbred defect.
So the same family wanted to rule Europe and the mommy gave them all haemophillia.
That is not in-breeding.
I would have thought an astute Cancer Pioneer could have discerned the difference in that respect.

Err… it shows the inter-relatedness of the royal families of Europe though.

Yes, but not the effects of “In-Breeding”!
The OP makes it sound like every King and Queen in Europe was encouraging as much brother-sister knobbing as the Pope would allow making their children slope-headed chinless wonders.

I can see the OP looking for a giggle factor.

First off, a dominant trait is just passed to descendants. Most deleterious genes, however, are recessive and in-breeding definitely increases their prevalance. IIRC, hemophilia is a sex-linked recessive, which basically means it passes from maternal grandfather to grandson, with the mother not suffering from it (unless she gets a double dose). As far as I can see, the main effect on the royal family from in-breeding is dim-wittedness. I will refrain from giving examples.

If he is, he needs to get a copy of Royal Babylon.

But, AFAIK, (IANAGeneticist), most inbred defects are just inherited defects that non-inbred people could have as well. They’re just more likely to show up in an inbred individual, especially in the case of something like Tay-Sachs or cystic fibrosis where the affected individual has two recessive genes.

Didn’t you read Anne’s link? They were super-chinned wonders!

The allele is located on the X chromosome, so you could get it from either your mother or your father, although if your father has it, he would know. It can also occur as a mutation, so you might be the first individual in your family to get it.

AFAIK, none of the European royalty got hemophilia because of inbreeding, but an example of that would be, hypothetically, if Prince A (hemophiliac) marries Princess B (carrier) and they have a daughter who is affected. This assumes, of course, that A and B got their hemophilia allele from their same grand-parent (however distantly). The same allele would have found its way into the daughter via two different paths.

Of course, we’re all pretty closely related, so whenever you get two recessive alleles that cause a genetic defect they may have originally come from the same source-- it’s just that we don’t keep our family histories as well as the Royals do.

Any case where a person gets two copies of the same recessive gene is ultimately due to inbreeding, just very, very distant inbreeding. If a person gets a copy of the Tay-Sachs gene from both parents, then way back when, both parents had a common ancestor who had the gene. There’s not any magic number for degree of relatedness beyond which breeding is safe; it’s just that the further apart you go, the lower the chance is of a problem. But occasionally, even with parents with no traceable family connection, it happens.

Not quite. As I noted in my previous post, hemophilia can be caused by a spontaneous mutation. It’s estimated that 30% of the cases of hemophilia are the result of such mutations.

What do you base this on? Is it a claim limited to recessive genes alone, even though dominant genes inherit in the same manner? Are you saying the Tay-Sachs gene only originated once, and everyone who has it got it from the person who originated it?

(The beginning of the quote makes sense to me, in that everyone has common ancestors. It’s the end that puzzles me, the certainty that any two people [of different gender, I suppose] who share a gene have a common ancestor with that same gene, who is ultimately responsible for their inheritance of it.)

Anything else?

While it is possible for the same mutation to happen in two unrelated individuals (see “cancer” or the hemophilia cases mentioned by John Mace), such work as DNA-testing for parentage or telling people where their ancestors were from based on an analysis of mytochondrial/Y-chromosome DNA work on mutations that are known (or moreorless known) to have come from a single point.

Sort of like saying “if you’re black you can be from Australian Aborigine ancestry, but most people would assume you’re from Subsaharian ancestry - because most black people are from Subsaharian ancestry.” (Let’s not get this hijacked by the whole ‘do races exist’ thing, ok, y’all know perfectly well what I mean by ‘black’)

DNA testing for parentage is of limited use once you go back more than a couple generations. You get your mtDNA and your Y chromosome from only 2 great-great-…-grandparents, the number of which increases geometrically (at least for a few generations before you start getting convergence of genetic lines).

“Black” isn’t a useful designator as there are many populations around the world that can be called “Black”. I honestly don’t know what you mean by that term.

I had presumed that, with as many possibile mutations as there are, it would be overwhelmingly improbable for the same mutation to occur independantly in two different individuals. Is this incorrect? One does occasionally see two different mutations on the same gene, which might have similar effects or interact in interesting ways, but they’re still distinguishable.

Here is a snapshot of the very interbred royal family trees of Europe.

Negative consequences? How about the War of the Spanish Succession?

To expand on a previous answer, due to inbreeding, Carlos II of Spain, called “el Hechizado” (the Bewitched). His mother Mariana of Austria was his father Philip IV’s niece, and his grandmother Maria Ana was also his aunt. As a result, his paternal grandparents were also his maternal great-grandparents, and to make matters worse, one set of paternal great-grandparents were also maternal great-great-grandparents on the other side. And it goes on.Here’s his family tree.

Anyhow, he was physically and mentally disabled; his jaw was so large he couldn’t chew and his tongue was so huge he could scarcely talk. As a result of all this, he was a complete invalid and, fairly obviously, never begat an heir, despite two unfortunate women from fertile families being chosen successively as his brides.

Consequently, when he died, the Spanish Habsburgs died with him; the throne threatened to pass into the control of Louis XIV via Philippe, Duke of Anjou. The War of the Spanish Succession immediately broke out, and after eleven years of fighting, Philippe became king anyway.

Upshot: don’t fuck your niece. It could cause a world war.

(I will note that there is a useful trend towards marrying unrelated commoners. The current Queens of Sweden and Norway were commoners, as were the current Crown Princesses of the Netherlands, Denmark, Spain, and Norway. That should introduce a little hybrid vigour.)

There are many different types of mutations, and some are more common than others. For example, every time a Downs Syndrome child is born, that is due to a new mutation. Gene duplication is another common type of mutation that can occur in multiple individuals at different times-- the severity of the genetic disorder is often a function of how many times the gene has duplicated itself. At any rate, no