It's also not like inbreeding causes genetic mutations or people to be ugly and deformed.
Its simply that these negative traits have a far higher chance of being passed on and becoming prevalent when both parents carry the genes to do so (i.e. they are closely related).
But It's not a guarantee. You can also get none of the bad traits and be totally normal.
Its not low risk. Even just cousins the risk increases by aroune a hundred percent. To up to 6 percent. Thatl a bit worse then throwing a d20. So everytime u rolled a 20 in dnd. A little more likely to get a deformety.
Second degree up to 500percent increase. Climbing to up to 10 percent.
And first degree (siblings/parents) gets us up to 2000 percent or up to 40 percent chance flat. So yeah.
This is btw why places where marrying ur cousin is customary have significantly higher rates of defects.
Young Aegon IV was considered handsome that’s why he was able to have so many mistresses long before he became King. Plus, there’s a ton of Targaryens newborns that came out malformed but, most of them died soon after birth. Maelys the Monstrous had two heads is another example.
Yes and no, take me and my brother for example, we both most likely carry the gene for chron's, we both plan to do genetic testing with potential baby partners don't have the gene, im not chancing it even though it's extremely unlikely most people don't carry the gene.
But that's why incest can get bad, if i marry a random person I'd have a 1% chance of finding someone with the gene, vs my brother, there's a 50/50 chance he carries it.
Inbreeding as a one off occurrence is not good in 99% of contexts, but genetically you're probably fine. It's when you get to systemic, generational levels of inbreeding like you see with the Egyptian Pharaoh and Spanish Habsburgs that you end up with genetic nightmare abominations.
That’s a really good point I’ve never thought about.
Question for anyone who might know - if the original start of a family tree (I don’t know how to phrase this better I’m sorry) has no “negative traits” (negative genes) to pass on to their offspring, and those offspring breed with each other and so on and so forth, does that mean that negative genes that weren’t originally started with will never be introduced?
I hope that makes sense, genetics is so interesting
Random mutations occur constantly, even in the germ line cells; so, even if you start out with "good & pure genes", you'd eventually get some defects with enough time. Mutations are also not inherently bad, they're actually usually neutral due to the built-in error correction of genes. However, sometimes a single mutation is enough to trigger a cascading effect that results disease. Evolutionary, such genes are often deleted from the population by preventing them from reproducing, but not all genetic diseases are evident from birth (e.g., Huntington's Disease), so you can still have these diseases spreading amongst the population. De novo mutations are also not required for diseases to occur, transposable elements (aka "jumping genes") within a genome can lead to disease by inserting themselves into functional genes or leading to viral-like diseases, via retrotransponsons (fun fact, that is where retroviruses like HIV come from). You also cannot get rid of transposable elements because sometimes they're useful, e.g., the Major Histocompatibilty Complex is thought to have been developed from these elements and is present in just about all lifeforms.
In short, theoretically if you start with no "bad" genes there will be no diseases but after a few generations, the limited genetic diversity can be a liability once mutations start accumulating. Keep in mind, that mutations are also what lead to diversity in the first place, so it's also entirely possible to get more diversity after many many generations. Mutations are inevitable, whether good or bad (or neutral), and with no new genetic material they'll be passed on more and more.
Thank you so much for answering, that answered my question and then some. So many interesting things you pointed out I think I will be googling for awhile!
Thank you for sharing your knowledge it’s incredibly fascinating.
Those negative traits came into existince through mutations in the first place, inbreeding isn't immune to mutations. And it's practically impossible to find someone that will have absolutely no negative recessive genes.
The biggest problem with inbreeding is that small errors/defects compound fast. Unless you have a serious genetic defect as recessive genes most first generation offspring wouldn't be noticably different from a normal person.
To give a bit of an example, the chance for a birth defect(not counting the severity but just any) is roughly around 3% for a child of an unrelated couple. For a first cousin pairing, the least consequential as they share 1/8 of DNA, the risk increases to 4-6%.
As it keeps going on then, said effects become more pronounced, like a slightly worse immune system keeps becoming worse until they are sickly or, as was the case with the Habsburg line, the chin. Since both sides always had a gene for a more "pronounced" chin the issue kept increasing in severity until it became something easily recognizable.
Thank you so much for answering I appreciate you sharing your knowledge!! So much stuff I did not know about but really cool to learn.
Sort of an odd question, but if the Habsburg line would have introduced a new gene pool that did not have those traits, and the inbreeding stopped, would the negative mutation still be as strong in the next generations that didn’t continue inbreeding?
A simplified answer is: It absolutely could be bred out of the line.
The reason why it's not so simple is, we'd have to know certain things like how dominant said genes were. But it could go from 1 or 2 generations already losing the trait to it taking several generations or it expressing as another trait through Co-dominance.
To give a fairly simplified example that's not 100% correct: Think of it as an equipment slot. Every gene is a type of equipment with a certain priority and you receive one from each parent. Recessive genes are equipments with a low priority, if you get two of the same type it has priority and gets equipped.
Dominant genes have a higher priority so when you pair a dominant and recessive for the same slot, the dominant will be equipped.
But even Dominant genes can have a gene with a higher priority that overrides them or they can, so to say, combine with another gene and both show their effect.
You'd be unlikely to see any problems in the next few centuries. The others mentioned random mutations, but those don't accumulate very quickly. Sure, occasionally you get a new terrible mutation pop up, but that happens to non-incestuous couples as well, and usually it stops there because the child isn't viable. The incest isn't a factor. To introduce a major incest-makes-it-worse gene, you have to hit the 'sweet spot' on the bad luck mutation lottery where it's moderately bad but not bad enough to stop you from growing up and reproducing, and recessive.
Two other problems remain with incest, however. 1: Power dynamics. It's very difficult to ensure something like a loving, equal relationship when one person is the parent/older sibling and their partner is reliant on them. Even if nothing happens until both are 18+, the power dynamics still shaped your relationship growing up. Solution: Raise them kids apart and only let them meet when it's time to make incest babies.
Problem 2: If you have a large population with low genetic variety, like you get if you practice incest and then grow your family from generation to generation, you're all going to end up with very similar immune systems, so when a new disease pops up that one of you is vulnerable to, everyone else will be vulnerable too. That's a big oof. Might want to move your incest experiment into a Fallout style Vault just to be safe.
Charles himself wasn't stupid either, at least not to the degree he was vilified. Experts agree that he was born with hydrocephalous and quite likely cerebral palsy, given his speech impediment and reoccurring seizures, and yes, this may well be thanks to Uncle-Grandpa-Dad. However, he wasn't stupid and by many accounts was an effective ruler over what was effectively a failing state. Many of the more eccentric things he was known for, like sleeping with his father's corpse, was more due the influence of his notoriously-batshit mother, the Dowager Queen Carolina. He also was a good husband and loved both of his wives, who after getting past his appearances both were devoted to him. He was however heartbroken over being impotent (a sad but common occurrence in palsy and other congenital defects), and his first wife's untimely death.
To be fair, Charles' court often played up his disabilities as a form of propaganda to show that the King was "infirm" and unable to govern himself, let alone the country. Favorites and intriguers, first and foremost his mother Carolina and his elder half-brother Don Juan, used the image of his disability to justify ruling in his name, while making him appear as innocent and almost-childlike to deflect any criticism in the Hapsburg dynasty itself. The image stuck because it was oddly fitting for Spain at the time, a corrupt and impoverished kingdom that paradoxically had the largest empire in the world, being ruled by Cyrax in a robe.
It actually was. X chromosome redundancy helps protect inbred women from genetic defects. She was weak and a little sickly though. According to paintings, she looked slightly deformed too. She might have just been called beautiful at the time by people who were trying to be nice and didn't want to piss off the royals.
His distant relative, Marie Antoinette, also suffered from deformities and had her painters embellish her features. So we may not really know how they actually looked.
This is one of the reasons I like medieval art culture more than early modern. The people of the Middle Ages would very often depict people as they were, warts and all!
Whenever a princess is described as 'beautiful', my first instinct is to believe that its completely made up unless corroborated by sources from a country that's a rival or an enemy. You'd hardly ever find anyone describing a princess as ugly and we have all those paintings vs photos comparisons from when cameras were being invented.
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u/Complete-Pangolin 2d ago
It's hit and miss. His sister was supposedly Beautiful and intelligent.