Can inbreed be beneficial?

[Damon_Tor]

1 hour ago, Lady Blizzardborn said:

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.

The problem is, we have no idea how any of it works. The suggestion that Targaryens are supposedly prone to dragon-like birth defects seems to support the idea that they were modified to be able to bond with dragons. And these birth defects seem to arise when the Targaryen is outbreeding, so why would that be?

The only good answer is in what I posted earlier: the Targaryens have genes that both add dragon traits as well genes that suppress some of those traits. As long as you have the full set, you're okay, you've got... whatever it is the bloodmages designed them to be. Absurdly capable dragon-riding badasses who can see the future. But you mix in some muggle and all of a sudden you've got people going mad and dead babies being born with horns. And sometimes you get a pretty regular muggle too.

At this point there's not much to do about it: the muggle admixture is in too deep, too many of the transgenic traits were lost. That's why the Targaryens are looking to other magic bloodlines to fill in the gaps.

[Amris]

To get back to the OP and in addition to my earlier post:

While it is theoritically possible to have a beneficial outcome through inbreeding (at the cost of an equally likely chance of getting a negative outcome instead) one has to keep in mind that this theoretical positive chance has a caveat: the only genetic traits that you can (possibly) keep pure through inbreeding are the traits that the parents already have. (Here: dragon-riding).

BUT since inbreeding by definition precludes crossing in traits from outside populations you can not improve the family traits with something that the family does not already have.

That's a serious disadvantage in the long run (as long as there is natural selection):

As an example let's assume some part of population A is naturally resistant to disease D and some portion of population B is naturally resistant to disease E.

If you keep inbreeding population A some of their descendents will also be resistant to disease D but they will never become resistant to disease E. And vice versa. 

Once the populations crossbreed there will eventually turn up some descendants who are resistant to both diseases. Whether disease D hits or disease E or even both: some descendants will be resistant and survive. Thus the species is saved.

It's small consolation if you can ride a dragon but then die of a disease because your gene-pool is not variable enough to cope.

[norwaywolf123]

11 hours ago, Damon_Tor said:

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.

Thank you for a good and intresting answear  

[Damon_Tor]

7 hours ago, Amris said:

While it is theoritically possible to have a beneficial outcome through inbreeding (at the cost of an equally likely chance of getting a negative outcome instead) one has to keep in mind that this theoretical positive chance has a caveat: the only genetic traits that you can (possibly) keep pure through inbreeding are the traits that the parents already have. (Here: dragon-riding).

BUT since inbreeding by definition precludes crossing in traits from outside populations you can not improve the family traits with something that the family does not already have.

And I think we're seeing that in the story: the Targaryens (some of them) are actively seeking out particular bloodlines, families that hadn't previously interbred with the Targaryens, presumably to acquire traits possessed by those families. I debate, I suppose, is whether they're doing that because there's something missing from their original design (assuming they were engineered via transgenics) or whether they had lost a trait due to prior outbreeding.

The possibility to transgenic manipulation is what changes the calculation here. If they were literally immune to infection prior to the Doom (as is suggested) then being worried about resistance to a particular disease wouldn't be a a factor. The Valyrian dragonlords were by most accounts stronger, smarter, and generally fitter than any baseline human.

[Lady Blizzardborn]

14 hours ago, Damon_Tor said:

The problem is, we have no idea how any of it works. The suggestion that Targaryens are supposedly prone to dragon-like birth defects seems to support the idea that they were modified to be able to bond with dragons. And these birth defects seem to arise when the Targaryen is outbreeding, so why would that be?

The only good answer is in what I posted earlier: the Targaryens have genes that both add dragon traits as well genes that suppress some of those traits. As long as you have the full set, you're okay, you've got... whatever it is the bloodmages designed them to be. Absurdly capable dragon-riding badasses who can see the future. But you mix in some muggle and all of a sudden you've got people going mad and dead babies being born with horns. And sometimes you get a pretty regular muggle too.

At this point there's not much to do about it: the muggle admixture is in too deep, too many of the transgenic traits were lost. That's why the Targaryens are looking to other magic bloodlines to fill in the gaps.

Prince Daemon and Laena Velaryon (whose mother was a Targaryen) also had a deformed baby. How much outbreeding is necessary to bring out the issue? Rhaenys herself had a Baratheon mother, but if Orys was in fact a half-brother to Aegon I, then there's dragonblood there too. And we've no reports of deformed babies from numerous Targ to non-Targ marriages.

Aenys I married a Velaryon. They didn't have any deformed babies.

Lady Rhaena married a Hightower and had six daughters. No mention of any deformities. Same with Viserys I and Alicent Hightower.

Viserys II's children with a Lyseni noblewoman were all healthy.

Elaena Targaryen had four children with her Penrose husband. No mention of any problems.

The Targaryen-Arryn marriages didn't produce deformation. Nor the Targaryen-Tyroshi marriages.

Daeron II's Martell marriage produced healthy kids. As presumably did his sister's marriage Martell marriage.

Baelor Breakspear's sons with Jena Dondarrion were fine.

Maekar's boys with Dyanna Dayne were okay.

Aegon's children with Betha Blackwood had no issues.

Princess Rhaelle married Lord Ormund Baratheon. At least one child. No mention of any deformities in that one or the next generation.

It doesn't seem to be as simple as outbreeding causing the issues. If that were the case then Daemon and Rhaenyra's daughter Visenya should have been fine, unless you think there's a generation skipping aspect to it. Rhaenrya's mother was half Arryn.

[Daemon]

41 minutes ago, Lady Blizzardborn said:

Maekar's boys with Dyanna Dayne were okay.

 

Not all Maekar's boys were okay.Aerion Brightflame was really mad and cruel

We can assume that by his death.He drink a  cup of wildfire, believing it would transform him into a dragon.

[Damon_Tor]

50 minutes ago, Lady Blizzardborn said:

It doesn't seem to be as simple as outbreeding causing the issues. If that were the case then Daemon and Rhaenyra's daughter Visenya should have been fine, unless you think there's a generation skipping aspect to it. Rhaenrya's mother was half Arryn.

Yes.

So again, remember how I said that Valyrians could have two sets of genes: a set of dragon genes and a set of genes that switch off some of those dragon genes.

We'll call the Dragon genes D and the counter genes X. Normal humans will have both d(no dragon genes) and x(no counter genes).

A pure Valyrian would have the genes DD XX resulting in the exact amount of dragon traits expressed to result in enhanced intelligence, strength, vitality, and of course dragonriding.

A pure human would have the genes dd xx, for no enhanced abilities.

When a pure Valyrian crossbreeds with a baseline human, the result is a first generation hybrid, and the genetic results are predictable: Dd Xx. It's possible that this genotype results in a perfect Valyrian, or that it results in a somewhat diminished Valyrian.

But once these first generation hybrids start breeding together, or breeding back into a pure population, we start getting some potentially horrible results:

Two first generation hybrids (Dd Xx) interbreed and we wind up with a crap shoot of possible results:

• Dd Xx: Same as the parents, the functional but perhaps diminished Valyrian
• DD XX: A true Valyrian reborn
• dd xx: A regular human.
• DD xx: All the dragon genes, none of the off switches. This could be the deformed stillborns
• Dd xx: Some of the dragon genes none of the off switches. Also deformed?. Maybe these are the ones that live for a bit then die. Maybe this is the madness?
• DD Xx: All of the dragon genes, not enough of the off switches. Maybe this is the madness?
• dd Xx: Do the "off switch" genes do anything without dragon genes? Maybe these are just normal humans too. Who knows.
• dd XX: Same notes as above
• Dd XX: Too many off switches? Perhaps a greatly diminished Valyrian? Just barely above average human? Unsure.

And I think this is pretty much the state of the Targaryen line, and the noble families that have married Targaryens, right now, a mix of hybrids of various abilities.

And remember that while Velaryons were Valyrian, they were not dragonlords. The may have had the standard ethnic traits of Valyrians (hair, eyes) but may not have carried any of the genes responsible for dragonriding, or if they did, may not have always had those genes in a heterozygous state.

EDIT: Left out a genotype

[Damon_Tor]

Just now, Daemon said:

Not all Maekar's boys were okay.Aerion Brightflame was really mad and cruel

We can assume that by his death.He drink a  cup of wildfire, believing it would transform him into a dragon.

Part of the problem here is that it's been suggested that some of the Targaryen madness wasn't madness at all, but manipulations by psychics such as Bloodraven. They thought they were hearing voices because they were.

[Dorian Martell's son]

On 8/11/2017 at 8:27 AM, norwaywolf123 said:

Has inbreeding with eugenic aims ever been tested?

Hitler didn't have time. With that whole committing suicide when he realized he was a total failure 

On 8/11/2017 at 0:59 PM, norwaywolf123 said:

Can recessive genes become dominant?

Yes, when there are not enough breeding individuals available

On 8/11/2017 at 0:59 PM, norwaywolf123 said:

Why do evolution get rid of Dominant genes?

If dominant genes are not successful, they will eventually be bred out of the population 

On 8/11/2017 at 0:59 PM, norwaywolf123 said:

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

Yes, eye color is also a result of natural selection

On 8/11/2017 at 0:59 PM, norwaywolf123 said:

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

Yes. If a gene is responsible for regulating something necessary for survival, it is purely positive. If a gene, when present expresses a trait that makes survival difficult, then yes, it is purely negative. This is why genetic diversity is very important to survival. 

On 8/11/2017 at 0:59 PM, norwaywolf123 said:

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

Nope. Eventually, as the inbreeding continues, the dice all end up with nothing but 1s on them

On 8/11/2017 at 0:59 PM, norwaywolf123 said:

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

In the fantasy, maybe. In the real world, outbreeding offers an influx of viable genetic code that will improve offspring 

On 8/11/2017 at 0:59 PM, norwaywolf123 said:

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

The issue would be the traits you are breeding for. Take Dogs. most inbreeding is to get dogs to look a specific way. These poor mutant dogs that are bred for appearance usually have behavior ignored

[norwaywolf123]

3 hours ago, Damon_Tor said:

And remember that while Velaryons were Valyrian, they were not dragonlords.

They did become dragonlords though maybe becouse of their relationship wiht House Targaryen. I wonder how the Celtigars were connected with the Targaryens and velaryons? Where they one unit from a genetic perspective? Maybe these 3 valyrian houses interbreed for many generations?

[Lady Blizzardborn]

4 hours ago, Daemon said:

Not all Maekar's boys were okay.Aerion Brightflame was really mad and cruel

We can assume that by his death.He drink a  cup of wildfire, believing it would transform him into a dragon.

We're talking about the physical deformities of the "dragon babies" who were born dead. None of Maekar's kids were born with wings or a tail.