I think it's a great misconception that incest in general causes major problems IRL. Only prolonged (over multiple generations), concentrated and somewhat isolated incest causes really significant problems. If siblings occasionally produce offspring no problems are to be expected, aside from consequences stemming from the taboo. I guess our aversion for it (culturally expressed in fiction) mainly protects us from devastating large scale spread. As long as the influx of new genetic material is secured everything is fine biologically speaking.

robertbmilesb14_ESO wrote: »

LennoxPoodle wrote: »

I think it's a great misconception that incest in general causes major problems IRL. Only prolonged (over multiple generations), concentrated and somewhat isolated incest causes really significant problems. If siblings occasionally produce offspring no problems are to be expected, aside from consequences stemming from the taboo. I guess our aversion for it (culturally expressed in fiction) mainly protects us from devastating large scale spread. As long as the influx of new genetic material is secured everything is fine biologically speaking.

https://www.psychologytoday.com/us/blog/animals-and-us/201210/the-problem-incest

A near 50% chance at birth defects is not a misconception.

https://www.ncbi.nlm.nih.gov/pubmed/23470695

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1504045/?page=1

etc.

I stand corrected then, although the text assumes that the genome of siblings is 50% identical, which is only true in average (it can theoretically range from 0 to 100%). The evidence is also relatively bad with the last link doubting the credibility of the largest study (161 children), which leaves a sample size of 31 for the two maybe less biased (due to selection/social background in the larger Czechoslovakian study. It has to be mentioned though, that the control group was exceptionally well chosen). The coherence of the results for all studies make it seem very legit though. I guess this warrants a computer simulation or large scale experiment. I'm not specifically referring to humans here or in my first post.

LennoxPoodle wrote: »

robertbmilesb14_ESO wrote: »

LennoxPoodle wrote: »

I think it's a great misconception that incest in general causes major problems IRL. Only prolonged (over multiple generations), concentrated and somewhat isolated incest causes really significant problems. If siblings occasionally produce offspring no problems are to be expected, aside from consequences stemming from the taboo. I guess our aversion for it (culturally expressed in fiction) mainly protects us from devastating large scale spread. As long as the influx of new genetic material is secured everything is fine biologically speaking.

https://www.psychologytoday.com/us/blog/animals-and-us/201210/the-problem-incest

A near 50% chance at birth defects is not a misconception.

https://www.ncbi.nlm.nih.gov/pubmed/23470695

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1504045/?page=1

etc.

I stand corrected then, although the text assumes that the genome of siblings is 50% identical, which is only true in average (it can theoretically range from 0 to 100%). I'm curious for the reasons though. I know it increases the chance of hereditary genetic issues occurring, but that difference seems rather extreme (for first gen inbreeding).

I apologize if you didnt want the biology lesson. Essentially, it amplifies the chance for one or more recessive genetic disorders if the parents are carriers of the recessive gene. Recessive genetic disorders arent the only issues incest can cause, but its the easiest to explain.

On average, siblings and parents share 50% of their genes (of the genes that actually vary in humans). That's a pretty good average, to be blunt, unless the parents have a lot of heterozygous traits (traits with one dominant and one recessive gene). The process of meiosis that gives half of each parent's DNA acts as a pretty good gene scrambler...but in the case of father/daughter incest, its like getting 3/4th of the potential DNA in the mix from the same person or in Brother/Sister, improves the chances for getting two copies of recessive or harmful genetic traits that their parents were carrying.

So an individual who's carrying a recessive gene doesn't have the disorder because they also have the dominant gene. If they have a child with another carrier (if you are a carrier, at least one parent is a carrier, and your sibling has a 50% chance to be a carrier) the chance of the child having double recessives is 25%. Now realize that there are numerous recessive disorders and that on average, Humans carry one to two lethal recessives, and you start to see why that 25% chance of getting at least one double recessive that causes problems of varying severity is actually pretty high in the case of sibling incest.

So the biggest problem for brother-sister incest is that if someone has got any recessive genes in their family that could cause issues, having a child with a sibling is just using the DNA of two people who each have at least a 50% chance of being a carrier for any given recessive.

You'd see a very similar problem for any two parents who know they are carriers for a recessive gene - such as if there's a known incidence of the disorder in their family history. However, in thise cases there is not a significant genetic overlap so while there might be a high risk for a particular genetic disorder, its not the same risk as incest where you have multiple chances to double any recessives the sibling's parents had carried.

In the case of children of incest who don't have any problems, they essentially won the genetic lottery. They didn't get any harmful recessive doubling or other problems. At 50 to 60%, its not fair to say they are the exception or the rule. I'd say rather that they were pretty lucky, genetically.

So this explains why incest causes a higher incidence of recessive genetic disorders - there's a 50% chance that each sibling will be a carrier, and if they are, there's a 25% chance their child will get both recessives. These genetic disorders made up a portion of that 40-50% of problems seen in the studied children that were the result of incest.

Hope that helps clarify a bit!

VaranisArano wrote: »

LennoxPoodle wrote: »

robertbmilesb14_ESO wrote: »

LennoxPoodle wrote: »

I think it's a great misconception that incest in general causes major problems IRL. Only prolonged (over multiple generations), concentrated and somewhat isolated incest causes really significant problems. If siblings occasionally produce offspring no problems are to be expected, aside from consequences stemming from the taboo. I guess our aversion for it (culturally expressed in fiction) mainly protects us from devastating large scale spread. As long as the influx of new genetic material is secured everything is fine biologically speaking.

https://www.psychologytoday.com/us/blog/animals-and-us/201210/the-problem-incest

A near 50% chance at birth defects is not a misconception.

https://www.ncbi.nlm.nih.gov/pubmed/23470695

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1504045/?page=1

etc.

I stand corrected then, although the text assumes that the genome of siblings is 50% identical, which is only true in average (it can theoretically range from 0 to 100%). I'm curious for the reasons though. I know it increases the chance of hereditary genetic issues occurring, but that difference seems rather extreme (for first gen inbreeding).

I apologize if you didnt want the biology lesson. Essentially, it amplifies the chance for one or more recessive genetic disorders if the parents are carriers of the recessive gene. Recessive genetic disorders arent the only issues incest can cause, but its the easiest to explain.

On average, siblings and parents share 50% of their genes (of the genes that actually vary in humans). That's a pretty good average, to be blunt, unless the parents have a lot of heterozygous traits (traits with one dominant and one recessive gene). The process of meiosis that gives half of each parent's DNA acts as a pretty good gene scrambler...but in the case of father/daughter incest, its like getting 3/4th of the potential DNA in the mix from the same person or in Brother/Sister, improves the chances for getting two copies of recessive or harmful genetic traits that their parents were carrying.

So an individual who's carrying a recessive gene doesn't have the disorder because they also have the dominant gene. If they have a child with another carrier (if you are a carrier, at least one parent is a carrier, and your sibling has a 50% chance to be a carrier) the chance of the child having double recessives is 25%. Now realize that there are numerous recessive disorders and that on average, Humans carry one to two lethal recessives, and you start to see why that 25% chance of getting at least one double recessive that causes problems of varying severity is actually pretty high in the case of sibling incest.

So the biggest problem for brother-sister incest is that if someone has got any recessive genes in their family that could cause issues, having a child with a sibling is just using the DNA of two people who each have at least a 50% chance of being a carrier for any given recessive.

You'd see a very similar problem for any two parents who know they are carriers for a recessive gene - such as if there's a known incidence of the disorder in their family history. However, in thise cases there is not a significant genetic overlap so while there might be a high risk for a particular genetic disorder, its not the same risk as incest where you have multiple chances to double any recessives the sibling's parents had carried.

In the case of children of incest who don't have any problems, they essentially won the genetic lottery. They didn't get any harmful recessive doubling or other problems. At 50 to 60%, its not fair to say they are the exception or the rule. I'd say rather that they were pretty lucky, genetically.

So this explains why incest causes a higher incidence of recessive genetic disorders - there's a 50% chance that each sibling will be a carrier, and if they are, there's a 25% chance their child will get both recessives. These genetic disorders made up a portion of that 40-50% of problems seen in the studied children that were the result of incest.

Hope that helps clarify a bit!

I really enjoy biology lessons!

What the problem is, was clear for me. I just wasn't aware of the huge amount of average proplematic recessives. I just estimated the chance for problems to go up a single digit percentage or something along those lines.
Let me check (a simplified version of) the math here quickly. To pass on a given harmfull chromosome the chance is 50%. So the chance for brother and sister to have it both is 25%. The chance for both to pass that on (asuming both have it) is again 25%, resulting in a total of 12.5% for a first generation inbred child. With 2 chromosomes (used as average here, A harmfull combination(double recessive), B harmless) we get: AA(12.5%^2=1/64)+AB(1/8*7/8=7/64)+BA(7/64)=15/64=23.4375%
That's far below 50 but still alarming. There must be something else at play.

Does any evidence exist that creatures on Nirn are DNA based?

LennoxPoodle wrote: »

VaranisArano wrote: »

LennoxPoodle wrote: »

robertbmilesb14_ESO wrote: »

LennoxPoodle wrote: »

I think it's a great misconception that incest in general causes major problems IRL. Only prolonged (over multiple generations), concentrated and somewhat isolated incest causes really significant problems. If siblings occasionally produce offspring no problems are to be expected, aside from consequences stemming from the taboo. I guess our aversion for it (culturally expressed in fiction) mainly protects us from devastating large scale spread. As long as the influx of new genetic material is secured everything is fine biologically speaking.

https://www.psychologytoday.com/us/blog/animals-and-us/201210/the-problem-incest

A near 50% chance at birth defects is not a misconception.

https://www.ncbi.nlm.nih.gov/pubmed/23470695

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1504045/?page=1

etc.

I stand corrected then, although the text assumes that the genome of siblings is 50% identical, which is only true in average (it can theoretically range from 0 to 100%). I'm curious for the reasons though. I know it increases the chance of hereditary genetic issues occurring, but that difference seems rather extreme (for first gen inbreeding).

I apologize if you didnt want the biology lesson. Essentially, it amplifies the chance for one or more recessive genetic disorders if the parents are carriers of the recessive gene. Recessive genetic disorders arent the only issues incest can cause, but its the easiest to explain.

On average, siblings and parents share 50% of their genes (of the genes that actually vary in humans). That's a pretty good average, to be blunt, unless the parents have a lot of heterozygous traits (traits with one dominant and one recessive gene). The process of meiosis that gives half of each parent's DNA acts as a pretty good gene scrambler...but in the case of father/daughter incest, its like getting 3/4th of the potential DNA in the mix from the same person or in Brother/Sister, improves the chances for getting two copies of recessive or harmful genetic traits that their parents were carrying.

So an individual who's carrying a recessive gene doesn't have the disorder because they also have the dominant gene. If they have a child with another carrier (if you are a carrier, at least one parent is a carrier, and your sibling has a 50% chance to be a carrier) the chance of the child having double recessives is 25%. Now realize that there are numerous recessive disorders and that on average, Humans carry one to two lethal recessives, and you start to see why that 25% chance of getting at least one double recessive that causes problems of varying severity is actually pretty high in the case of sibling incest.

So the biggest problem for brother-sister incest is that if someone has got any recessive genes in their family that could cause issues, having a child with a sibling is just using the DNA of two people who each have at least a 50% chance of being a carrier for any given recessive.

You'd see a very similar problem for any two parents who know they are carriers for a recessive gene - such as if there's a known incidence of the disorder in their family history. However, in thise cases there is not a significant genetic overlap so while there might be a high risk for a particular genetic disorder, its not the same risk as incest where you have multiple chances to double any recessives the sibling's parents had carried.

In the case of children of incest who don't have any problems, they essentially won the genetic lottery. They didn't get any harmful recessive doubling or other problems. At 50 to 60%, its not fair to say they are the exception or the rule. I'd say rather that they were pretty lucky, genetically.

So this explains why incest causes a higher incidence of recessive genetic disorders - there's a 50% chance that each sibling will be a carrier, and if they are, there's a 25% chance their child will get both recessives. These genetic disorders made up a portion of that 40-50% of problems seen in the studied children that were the result of incest.

Hope that helps clarify a bit!

I really enjoy biology lessons!

What the problem is, was clear for me. I just wasn't aware of the huge amount of average proplematic recessives. I just estimated the chance for problems to go up a single digit percentage or something along those lines.
Let me check (a simplified version of) the math here quickly. To pass on a given harmfull chromosome the chance is 50%. So the chance for brother and sister to have it both is 25%. The chance for both to pass that on (asuming both have it) is again 25%, resulting in a total of 12.5% for a first generation inbred child. With 2 chromosomes (used as average here, A harmfull combination(double recessive), B harmless) we get: AA(12.5%^2=1/64)+AB(1/8*7/8=7/64)+BA(7/64)=15/64=23.4375%
That's far below 50 but still alarming. There must be something else at play.

Well, keep in mind that from the studies linked above, recessive genetic disorders were clearly only a possible result. There were a number of times that would occur, but the 40 to 50% problematic results also included mild to severe mental retardation, not just recessive disorders. I chose to focus on explaining the recessive genetic disorders precisely because its the easiest to explain with math (Punnett Squares, if you want to play with the math on dominant/recessive alleles even more). Mental retardation can have a lot more causes, related disorders and degrees of severity, so it doesnt break down quite as neatly.

For example, in the smaller study cited in the 2nd of the linked scholarly sources, 3 to 6 out of the 31 children had probable or known recessive genetic disorders (others had different problems). While that's such a small statistical sample that I caution you against putting too much weight on that percentage, it is closer to what I expect the actual occurence of recessive disorders to be (25% IF both siblings are carriers) the article does point out that the expected occurence of recessive genetic disorders in a normal population (I.e. two carriers have a child) is 2 or 3 cases out of a thousand people. 3 to 6 out of 31 cases is clearly much higher, and that's simply because siblings have a much higher chance of getting the same recessives because of the same source of their genetic material from their parents.

The 40% to 50% was for ANY harmful effect. That's pretty bad odds, and it looks like most of that statistical data did not count the sort of genetic problems that result in a non-viable fetus, so the total percentage if we could count that would probably be higher.

lordrichter wrote: »

Does any evidence exist that creatures on Nirn are DNA based?

I would have to go with "yes" due to the contents of the lorebook 'Fall of Vitharn' which detail the child of sibling incest having multiple recessive genetic abnormalities. If DNA did not exist then he would not have any of those and would simply be a regular child.

Sicerius420 wrote: »

how the *** did we get on this subject anyway

The Tharn family?