Can inbreed be beneficial?

[mr.archanfel]

We were told that "King Jaehaerys once told me that madness and greatness are two sides of the same coin. Every time a new Targaryen is born, he said, the gods toss the coin in the air and the world holds its breath to see how it will land.". 

So biologically speaking, since recessive gene (or allele) are more pronounced (not sure what's the right term) in children born from incest, can they actually be beneficial? Does Targaryen's idea of keeping the bloodline pure actually hold water scientifically much like pets are often bred to show certain traits? 

[Lady Winter Rose]

Real life speaking, children would have heart anomalies and intelligence and mental stability isssues. As far as I know, there would be no genious among them.

[The Fattest Leech]

No. Not in real life with animal or human, nor how George uses it in his stories. It is a form of extremism and the hippy author doesn't reward extremist practice in anyway. 

The idea that breeding horses and dogs the way we do improves them is false. Especially with the smaller, more frequently bred animals like dogs, cats, etc. Seriously, there are a lot of negatives that goes into it that you should research because that would take a whole page to list.

In the books George is seemingly not using all of the real world science to explain incest, because the Targaryens would in no way be as beautiful as they are if that was so. He is using some aspects, but not all. It is fantasy, after all. 

Same with humans. Despite what some customs of might practice, the side effects are staggeringly negative. And again, incest was usually reserved for the elite, and we know what happened to families, including but not limited to, the Hapsburgs. Just about 3 years ago, an inbred family was discovered in Australia and the list of medical issues is long.

Now, in both ASOIAF and any of George's past work where incest is there in either suggestion or practice, it never succeeds. Ever. Each time it is either a personal fail or a societal fail, and more often than not the society rejects the incest idea even when the only option is that society dies out. If there are people who live in small communities, he has them get together in "gatherings" to have big orgies so they share genes within a large, not inbred, gene pool. 

The Targaryens practices incest as a way to control the dragon riding gene/talent/ blood. It was a form of enslaving their woman. The books, and George outside of the books, both say the Targaryens thought themselves above gods and men and that the rules don't apply to them. That is the arrogant and elitist ideal that George does not reward. 

Any bits of incest, including Tywin, is not about love or concern, but about control. The author has mentioned this before.  

George talk a little about inbreeding here:

http://www.westeros.org/Citadel/SSM/Entry/945

The Targaryens have heavily interbred, like the Ptolemys of Egypt. As any horse or dog breeder can tell you, interbreeding accentuates both flaws and virtues, and pushes a lineage toward the extremes. Also, there's sometimes a fine line between madness and greatness. Daeron I, the boy king who led a war of conquest, and even the saintly Baelor I could also be considered "mad," if seen in a different light.

---

and he also says he does not condone incest in this interview:

 

 

 

[Dofs]

It can only be beneficial if the parents don't have any bad recessive genes which is not realistic.

[kissdbyfire]

Short, sweet, and to the point: NO.

[Vaedys Targaryen]

First generation incest is actually not very likely to have birth defects.

Amazingly, two siblings can actually have children together and chances of the children having birth defects vary from study to study, but most agree that birth defects in first generation incest in <5%.

The problem begins when the incest continues for many generations, like with the Targaryens; you could argue that their blood is indeed magical and thusly they can be incestuous for many generations and only allow something new in every once in a while, but that is not reality. continuous incest, especially with siblings, will cause trouble the more generations they make.

[GyantSpyder]

"Beneficial" depends on what your goal is.

In a net overall sense, generally no. But sometimes there are weird situations. Nature is crazy.

For example, most grapevines in the world's vineyards are grafted to the same narrow variety of American grapevine roots, because a major blight in the 19th century that traveled from America to Europe and the rest of the world was destroying all the other varieties of wine grape. The blight still exists and there is no remedy for it.

Vineyards are able to keep diversity in the grapes, but only by giving up diversity in the root systems.

Attempting to plant a wider variety of grapevine roots would just result in your grapes dying and you vineyard going out of business.

 

[mr.archanfel]

1 hour ago, Vaedys Targaryen said:

First generation incest is actually not very likely to have birth defects.

Amazingly, two siblings can actually have children together and chances of the children having birth defects vary from study to study, but most agree that birth defects in first generation incest in <5%.

The problem begins when the incest continues for many generations, like with the Targaryens; you could argue that their blood is indeed magical and thusly they can be incestuous for many generations and only allow something new in every once in a while, but that is not reality. continuous incest, especially with siblings, will cause trouble the more generations they make.

However, is it also possible that it would create a brand new species or subspecies? 99 out of 100 times the new species would be inferior and die out, but every now and then, you would get a new species that is more adaptive to a new niche environment. In this case, fire immune (sometimes), heat tolerate and dragon taming. 

Having said that, Daenerys's bloodline is not that pure to begin with and historical Targaryen didn't have such power. Also, Targaryens can still interbreed with other humans. So maybe not. 

I also wonder whether dragons inbreed given the population bottleneck. Maybe that's why they got smaller and sickly. 

[norwaywolf123]

4 hours ago, mr.archanfel said:

We were told that "King Jaehaerys once told me that madness and greatness are two sides of the same coin. Every time a new Targaryen is born, he said, the gods toss the coin in the air and the world holds its breath to see how it will land.". 

So biologically speaking, since recessive gene (or allele) are more pronounced (not sure what's the right term) in children born from incest, can they actually be beneficial? Does Targaryen's idea of keeping the bloodline pure actually hold water scientifically much like pets are often bred to show certain traits? 

Inbreeding makes some traits more pronounced traits and recesive genes. Over time inbreeding increaes the chance that a baby will be porn with two alleles who when more than one will result in disability. Maybe if people practiced infanticide they could abort the babies negatively affected by inbreeding and chose the healty ones?

https://en.wikipedia.org/wiki/Inbreeding

[GyantSpyder]

Just now, norwaywolf123 said:

Maybe if people practiced infanticide they could abort the babies negatively affected by inbreeding and chose the healty ones?

Just a note that the Targaryans do have a tendency to give birth to deformed babies with Harlequin-esque / Dragon-esque deformities. So this may very well be what is happening over time for them.

[norwaywolf123]

1 hour ago, Lew Theobald said:

Moral issues aside, ... this is not very effective when the genetic defect manifests itself by a tendency towards madness that will be triggered by an adult traumatic experience; which is more or less what happened to Aerys.

It is easier to detect physical flaws but Aerys was healthy physically just mentally ill

[Clegane'sPup]

Targ reproduction and interbreeding has to do with the outlook that some individuals are superior to others, as in experiments carried out during WWII. It is not a new or unique thought process.

A Storm of Swords - Jon III      "Longspear's not your brother."   "He's of my village. You know nothing, Jon Snow. A true man steals a woman from afar, t' strengthen the clan. Women who bed brothers or fathers or clan kin offend the gods, and are cursed with weak and sickly children. Even monsters."

Commom sense. Bring all the scientific genetic info that can be applied. Rationalize and justify it in any way you would like. Mentally, physically, spiritually and emotionally inbreeding with one’s own blood relation is frowned upon for good reason.

 

[Dorian Martell's son]

10 hours ago, mr.archanfel said:

We were told that "King Jaehaerys once told me that madness and greatness are two sides of the same coin. Every time a new Targaryen is born, he said, the gods toss the coin in the air and the world holds its breath to see how it will land.". 

So biologically speaking, since recessive gene (or allele) are more pronounced (not sure what's the right term) in children born from incest, can they actually be beneficial? Does Targaryen's idea of keeping the bloodline pure actually hold water scientifically much like pets are often bred to show certain traits? 

Of course it can be beneficial. All your family looks exactly alike, small genetic diseases become super prominent and eventually your junk stops working and you fail to produce children and then your line dies off.  
https://en.wikipedia.org/wiki/House_of_Habsburg#Extinction_of_the_Spanish_Habsburgs
https://en.wikipedia.org/wiki/House_of_Habsburg#Extinction_of_the_Austrian_Habsburgs 

[Kaibaman]

I would go out on a limb here and say that although in real life incest leads to all kinds of birth defects, for the Valyrians it maybe not be the case. Remember these were not ordinary people, they used magic to allow themselves to control dragons and have partial resistance to heat so it could be reasoned that they may have also used magic as a form of genetic engineering to allow their descendants to interbreed. I find it rather strange why the Valyrians would do this at all instead of marrying into other families to form political alliances. But there has to be some benefit and obviously no downsides to it if in their society this was the norm.

[Amris]

Incest among close relatives increases the offspring's chances to inherit good traits as much as it increases the chances to inherit bad traits. That's because close relatives share more similar genes than complete strangers do.

However it is very complicated because there are still lots of possible combinations. Theoretically speaking if only say - 2 genes - were passed on then the equation could be:

parent 1: gene A: good/bad   gene B: good/bad      parent 2: gene A: bad/good   gene B: bad/good

possible results in offspring:

 

1: gene A: bad/bad    gene B: bad/bad

2: gene A: bad/bad   gene B: good/bad

3: gene A: bad/bad   gene B: bad/good

4: gene A: bad/bad   gene B: good/good

5: gene A: good/good    gene B: good/good

6: gene A: good/good   gene B: good/bad

7: gene A: good/good   gene B: bad/good

8 gene A: good/good   gene B: bad/bad

9: gene A: good/bad   gene B: bad/bad

10: gene A: good/bad   gene B: good/good

11: gene A: good/bad    gene B: good/bad

12: gene A: good/bad   gene B: bad/good

13: gene A: bad/good   gene B: bad/bad

14: gene A: bad/good   gene B: good/good

15: gene A: bad/good    gene B: bad/good

16: gene A: bad/good   gene B: good/bad

16 possible combinations for this very simplified example with only 2 genes. And that's when we have limited the two-gene math to one possible parent combination. Really the parents already could have 4 different versions of those 2 genes. Each. So multiply our 16 combinations by 4 to get 64 possible outcomes really. And that's with dominant/recessive traits not even considered yet.

Our 16 possible combinations above would have an only 1 in 16 chance of an entirely positive outcome. (5: good/good good/good)

The same 1 in 16 chance exists for an entirely bad outcome (Number 1: bad/bad bad/bad)

Additionally there is a 3 in 16 chance for a partially good outcome (6, 7 and 8) as well as a 3 in 16 chance for a partially negative outcome (2, 3, 4).

The other 8 in 16 outcomes are mixed combinations that are neither good nor bad but much like their parents.

 

So in effect:

4 in 16 chance for some improvement

4 in 16 chance for making it worse

8 in 16 chance for the same as the parents

 

(It gets different if dominant/recessive is taken into account since then one of the inherited gene copies is not expressed (either the good or the bad one). So half of the mixed gene descendants would then also express the positive gene while the other half of the mixed descendants would express the negative gene. But lets not overly complicate it and forget that for now.)

 

The math makes it obvious that the OP question is valid insofar as: Yes, it is possible (theoretically) that inbreeding can be beneficial. But if we look at even only the simplified equation above it is clear, that it comes at a heavy risk.

 

Breeding animals works in the long run by only allowing the successful crossbreeds to breed themselves (in our example above: the 4 in 16 somewhat improved ones). But that obviously does not work for humans. So inbreeding is practically guaranteed to lead to an increasing number of gene defects over time in human populations. Of course some of the less successful variants weed themselves out simply because they are not survivable. (We have an example of this in the infamous Targ miscarriages I guess). This would somewhat skew chances of the surviving offspring in favor of positive outcomes. But not enough.

 

AND of course the human genome is much, much, much longer than 2 genes. So there would be an astronomical number of variants for the descendents and the possibility that one of them inherits all the positive genes and none of the defective ones would be so small as to be virtually nonexistant.

 

The kicker question in the Targ story is: is dragon-riding really genetically coded into their DNA (and not into anyone else's). If it is then it seems indeed necessary for a dragonriding family to take their chances with inbreeding and accept the negative results to keep being able to ride their dragons.

If that's just a fairy tale and really anybody could ride a dragon then the Targs have unnecessarily burdened themselves with the negative results of this custom.

[norwaywolf123]

1 hour ago, Amris said:

Breeding animals works in the long run by only allowing the successful crossbreeds to breed themselves (in our example above: the 4 in 16 somewhat improved ones). But that obviously does not work for humans. So inbreeding is practically guaranteed to lead to an increasing number of gene defects over time in human populations. Of course some of the less successful variants weed themselves out simply because they are not survivable. (We have an example of this in the infamous Targ miscarriages I guess). This would somewhat skew chances of the surviving offspring in favor of positive outcomes. But not enough.

Has inbreeding with eugenic aims ever been tested?

[Damon_Tor]

On 8/9/2017 at 6:15 AM, mr.archanfel said:

We were told that "King Jaehaerys once told me that madness and greatness are two sides of the same coin. Every time a new Targaryen is born, he said, the gods toss the coin in the air and the world holds its breath to see how it will land.". 

So biologically speaking, since recessive gene (or allele) are more pronounced (not sure what's the right term) in children born from incest, can they actually be beneficial? Does Targaryen's idea of keeping the bloodline pure actually hold water scientifically much like pets are often bred to show certain traits? 

Evolution generally gets rid of traits that are both dominant and negative, but recessive negative traits can survive by "hiding" in carriers, people who have the gene but don't express it.

And this isn't just explicit diseases, like hemophelia or sickle-cell anemia or cystic fibrosis. recessive genes can lower intelligence slightly, lower muscle mass slightly, lower bone density slightly, etc.

Over millions of years we've accumulated thousands of negative recessive traits on all our chromosomes. Everyone carries some of them, and everyone has a few of them in the heterozygous state (two copies) and expresses that gene. It's one reason why some people are a bit dumber, weaker, or more prone to illness.

EDIT: An addendum. The same evolutionary forces that work to eliminate negative dominant genes help to propagate positive recessive genes; in this case, the LACK of the positive gene is effectively identical to having a negative dominant gene. Two sides to the same coin.

Every time you have a child, you're rolling dice. But when inbreeding occurs, those dice are loaded against you. Inbred children have a greater chance at expressing those negative traits because close family members are most likely to be carrying the same negative genes.

A few caveats: if you somehow have a perfect genome, inbreeding isn't a problem. This was brought up in Heinlin's Time Enough for Love, where the main character, Lazarus Long, was the end result of a eugenics program which resulted in him having a genome with absolutely zero negative traits. In this scenario, inbreeding would yield stronger offspring than outbreeding because you've artificially eliminated imperfections. Similarly, if the Valyrian blood magic left the Targaryens with a perfect genome there would be no problems with them inbreeding.

Another part of the problem is that, supposedly, Valyrians had non-human (dragon) genes. As such, we can't expect the normal evolutionary processes to apply, because what a particular gene does in one organism might be vastly different than what it does in another, making a dominant negative trait possible, because we're dealing with a transgenic process, not evolution. It's even possible to have a situation where a negative dominant trait can be negated with ANOTHER gene, even another gene on a different chromosome, even another gene that is itself a recessive trait.

So, yes. It's possible for a transgenic organism to be able to benefit from inbreeding. It may be that their madness isn't because of their inbreeding: their madness could be a result of their lapses in inbreeding.

[norwaywolf123]

3 hours ago, Damon_Tor said:

Evolution generally gets rid of traits that are both dominant and negative, but recessive negative traits can survive by "hiding" in carriers, people who have the gene but don't express it.

Can recessive genes become dominant?

Why do evolution get rid of Dominant genes?

3 hours ago, Damon_Tor said:

And this isn't just explicit diseases, like hemophelia or sickle-cell anemia or cystic fibrosis. recessive genes can lower intelligence slightly, lower muscle mass slightly, lower bone density slightly, etc.

Also physical traits like hair color, eye color and maybe height?

3 hours ago, Damon_Tor said:

Over millions of years we've accumulated thousands of negative recessive traits on all our chromosomes. Everyone carries some of them, and everyone has a few of them in the heterozygous state (two copies) and expresses that gene. It's one reason why some people are a bit dumber, weaker, or more prone to illness.

EDIT: An addendum. The same evolutionary forces that work to eliminate negative dominant genes help to propagate positive recessive genes; in this case, the LACK of the positive gene is effectively identical to having a negative dominant gene. Two sides to the same coin.

Does purely positive or purely negative genes exist? Don't a gene do a litlle of this and a little of that?

3 hours ago, Damon_Tor said:

Every time you have a child, you're rolling dice. But when inbreeding occurs, those dice are loaded against you. Inbred children have a greater chance at expressing those negative traits because close family members are most likely to be carrying the same negative genes.

If you are lucky with the dice will the children be stronger genetically or darwinistic?

3 hours ago, Damon_Tor said:

A few caveats: if you somehow have a perfect genome, inbreeding isn't a problem. This was brought up in Heinlin's Time Enough for Love, where the main character, Lazarus Long, was the end result of a eugenics program which resulted in him having a genome with absolutely zero negative traits. In this scenario, inbreeding would yield stronger offspring than outbreeding because you've artificially eliminated imperfections. Similarly, if the Valyrian blood magic left the Targaryens with a perfect genome there would be no problems with them inbreeding.

Then maybe house Targaryen outbreeding with non Valyrians might have increased genetic deficencies.

3 hours ago, Damon_Tor said:

Another part of the problem is that, supposedly, Valyrians had non-human (dragon) genes. As such, we can't expect the normal evolutionary processes to apply, because what a particular gene does in one organism might be vastly different than what it does in another, making a dominant negative trait possible, because we're dealing with a transgenic process, not evolution. It's even possible to have a situation where a negative dominant trait can be negated with ANOTHER gene, even another gene on a different chromosome, even another gene that is itself a recessive trait.

So, yes. It's possible for a transgenic organism to be able to benefit from inbreeding. It may be that their madness isn't because of their inbreeding: their madness could be a result of their lapses in inbreeding.

How wuld you plan a inbreeding program with eugenic results in mind? Would it even be possible?

[Damon_Tor]

1 hour ago, norwaywolf123 said:

1. Can recessive genes become dominant?
2. Why do evolution get rid of Dominant genes?
3. Also physical traits like hair color, eye color and maybe height?
4. Does purely positive or purely negative genes exist? Don't a gene do a litlle of this and a little of that?
5. If you are lucky with the dice will the children be stronger genetically or darwinistic?
6. Then maybe house Targaryen outbreeding with non Valyrians might have increased genetic deficencies.
7. How wuld you plan a inbreeding program with eugenic results in mind? Would it even be possible?

1. Short answer: kind of. When it comes down to it, all genes do is create proteins, chemicals that either serve some purpose or hormones that communicate with other cells to coordinate bodily functions. Most of the time, a dominant gene is one that produces a particular protein or set of proteins whereas a recessive gene does not. However, sometimes proteins are created in one form and then are changed into another form or eliminated entirely by other proteins created by other genes. So you could have a situation where a "dominant" (protein-creating) gene becomes ubiquitous (every member of a population has two copies so no variation is possible without a mutation) and another gene comes along (via mutation or from a different population) which creates a protein that destroys that first protein. Then whatever trait that first gene controlled would become a recessive trait, combined with the new gene.

2. Evolution tends to get rid of dominant negative genes. It will suppress a recessive negative gene, but the pressure isn't as strong.

3. Sure.

4. Yeah, and it varies from environment to environment as well: a gene which makes added melanin in the skin is beneficial near the equator (where the melanin protects against the sun) but detrimental towards the poles (where it inhibits Vitamin D synthesis).

5. It's a metaphor: I'm saying what you get in your genes is just luck. You could bang your sister and get a perfectly normal kid, but the odds are worse than if you were mating with someone from outside your immediate family.

6. Yes, it's possible.

7. The major problem is the ability for recessive traits to hide, and potentially skip generations. For creatures with very rapid breeding (mice, for example) it's fairly easy to judge whether an individual is carrying a recessive gene by mating it with mice who are expressing the trait (half the offspring will have the trait in this case). Once you're reasonably sure you know who has the trait and who doesn't (based on an adequate volume of data) you breed mice who don't carry the trait to eliminate it from the gene pool.

Breeding for a dominant trait is the same, just reversed. See the addendum in my post above.

Of course it takes too long in humans to be able to accumulate much data. That plus the fact that many of the traits were care about in humans are mental, and are not obvious at birth. There's also the ethical problem of telling people who is allowed to breed, and with who. All that said, I do believe the Citadel is doing all of this. Their medical knowledge is extremely advanced. I expect they understand genetics, even if they don't know how chromosomes work physically, they understand that certain traits are recessive and other traits are dominant.

[Lady Blizzardborn]

On 8/9/2017 at 8:15 AM, mr.archanfel said:

We were told that "King Jaehaerys once told me that madness and greatness are two sides of the same coin. Every time a new Targaryen is born, he said, the gods toss the coin in the air and the world holds its breath to see how it will land.". 

So biologically speaking, since recessive gene (or allele) are more pronounced (not sure what's the right term) in children born from incest, can they actually be beneficial? Does Targaryen's idea of keeping the bloodline pure actually hold water scientifically much like pets are often bred to show certain traits? 

Only in a fantasy series where it seems to be potentially originated in control of the dragons and keeping that control in the family.

In real life too much is bad. A small amount can reinforce some traits, but even that is a calculated risk and had to be balanced against the potential negatives. Definitely not a good idea to make it the basis of any breeding program.