Incestuous Relationships

A1lion835 · Oct 4, 2010

I hope that looking at this title didn't make anyone recoil in disgust.

What's wrong with incestuous relationships? In my book, nothing. Usually, people's objections are that it's wrong/immoral/sick/against God's wishes/makes mutant babies.

How is marrying your sister any more wrong/immoral/sick than marrying someone the same gender as you, or of a different race? People who are against those things are, in effect, saying "Nope, sorry, you two can't love each other like that, it's not allowed because *reason*." And we call those people close-minded, we say they hate gays and it's a bad thing, we say they're racist - so how can denying love between two relatives be okay?

Against God's wishes -- With no guarantee that God exists, or that God's wishes are for brothers and sisters not to marry, this really doesn't make any sense at all.

The only other objection (mutant babies) is the only one that could hold some ground...but it doesn't hold much. People with similar genes reproducing doesn't cause birth defects, but an increase in homozygotes. That means recessive traits which code for birth defects could be more common, or the opposite could happen and birth defects would occur less often.

Something that inbreeding does inevitably lead to is an increase of female carriers. In small populations, these carriers probably won't live long enough to reproduce, so it's not a problem, but in larger populations, more carriers would reproduce.

However, the numbers don't change that drastically. Don't forget that we're not forcing people to marry their relatives: we're simply allowing them to do it. The number of incestuous marriages would be very small, so we're talking about a small number of unions which could cause a small number of birth defects. Not only will natural selection eventually deal with the defects, but an abortion can be carried out -- as in a "normal" union -- if the fetus is shown to have severe birth defects.

Finally, these defects are only fatal after 2 or more generations of close inbreeding, varying depending on the number of defects the carrier has. Let's put the number of incestuous marriages / non-incestuous marriages in a population around 1/1000 (a number which seems fairly realistic). That means that the chance of having 2 consecutive incestuous generations is around 1 in a million. That's less than 300 cases in the US! As stated in the previous paragraph, abortions are always an option if the defects are severe enough, and natural selection will eventually weed out any highly-defected lines.

What are other people's thoughts?

1048576 · Oct 5, 2010

I've looked, but haven't been able to find the rate of significant defects in incestuous vs. non-incestuous relationships. I imagine that's the main moral obstacle that differentiates incest from other relationships. If you remove that obstacle, then nothing is left except the "icky" factor, which is a social construct and a poor argument, because it can theoretically be used to argue against any relationship (no marrying bald people.)

Namaste · Oct 5, 2010

Nomnomnomnom

Jun. · Oct 5, 2010

There are possibly millions of genotypes in our bodies not only determining the way we look but also determining many of our internal and bodily functions. An incestuous relationship forces recessive traits (harmful ones for the point of this argument) to surface due to lack of genetic diversity. It is not only deemed taboo by society but is also wrong in an evolutionary sense.

However there are always exceptions
If you love a family member in a manner to engage in sexual relations, your relationship is obviously going to have to be limited unless you want to risk an offspring that will suffer many hardships. This limits the bounds of the relationship and despite the feelings you have for one another it'll never be the same as a normal relationship due to the laws of nature and genetics.

Ballistics · Oct 5, 2010

How is one so bored that they have to rely totally on their sister or brother for affection. Go out into the world and cross your genes!

That being said I would like to point to dolphin sexuality, where incest is common, as well as homosexuality and ****. Mating is more often for fun than for reproduction.

Jun. · Oct 5, 2010

we aren't dolphins.

nor are we peas that can self fertilize.

vVv Rapture · Oct 5, 2010

A1lion835 said:
Finally, these defects are only fatal after 2 or more generations of close inbreeding, varying depending on the number of defects the carrier has. Let's put the number of incestuous marriages / non-incestuous marriages in a population around 1/1000 (a number which seems fairly realistic). That means that the chance of having 2 consecutive incestuous generations is around 1 in a million. That's less than 300 cases in the US! As stated in the previous paragraph, abortions are always an option if the defects are severe enough, and natural selection will eventually weed out any highly-defected lines.

What are other people's thoughts?

I'll first put it on the table that I'm against incest and any marriage based on it. Many reasons have already been stated (social taboo, genetically hindering, naturally unnecessary, etc).

However, on this point, this isn't necessarily true. Let me give an example:

A - Gene, harmless, non-fatal, dominant
a - Gene, harmful, fatal, recessive

Let's say a brother and sister come together and both are Aa. When those two have children, the Punit Square would look like this:

A a
A AA Aa
a Aa aa

75% of the children would potentially have no signs of the recessive gene, but the unlucky 25% would be afflicted by this gene and, according to it, would die. This is just one generation of inbreeding and is completely possible.

Just wanted to point that out.

A1lion835 · Oct 5, 2010

Ballistics said:
How is one so bored that they have to rely totally on their sister or brother for affection. Go out into the world and cross your genes!

That being said I would like to point to dolphin sexuality, where incest is common, as well as homosexuality and ****. Mating is more often for fun than for reproduction.

"How is one so bored?" Seriously? Did you not consider that two relatives could be in love, or are you denying that it's possible?

junkimchi said:
There are possibly millions of genotypes in our bodies not only determining the way we look but also determining many of our internal and bodily functions. An incestuous relationship forces recessive traits (harmful ones for the point of this argument) to surface due to lack of genetic diversity. It is not only deemed taboo by society but is also wrong in an evolutionary sense.

Why assume that the recessive traits are harmful? For all we know, these two siblings could have recessive genes which cause immunity to cancer. Best to spread that around, no? And even if the genes are harmful, it's not necessarily bad to inbreed when harmful diseases are present (I go over this in more depth in this post's last response).

As for tabooed by society, I'm going to be frank...who gives a ****? I go more in-depth (in a thoroughly non-vulgar fashion) in my next response.

vVv Rapture said:
I'll first put it on the table that I'm against incest and any marriage based on it. Many reasons have already been stated (social taboo, genetically hindering, naturally unnecessary, etc).

And are you against gay marriage? Interracial marriage? Both of these were just as taboo as incest in large portions of the US in the past century or two, and there're still many individuals against both of them. So "socially taboo" isn't an acceptable reason at all.

I'll go into genetically hindering in response to your argument about it.

Naturally unnecessary - This also isn't a factor. It's not necessary for white people to have children; our civilization would survive plenty fine without it. Plus, the food that would go to feed the white children could instead be sent around to the starving populations of the world*. Not only that, but humans on a whole would be less susceptible to skin cancer, since the black population would increase! We'd also have fewer dumb racist jokes.

* (Feeding the starving populations around the world is not what I consider a good idea, but that's for another argument. Other Debaters who have read Ishmael, by Daniel Quinn, will understand where I'm coming from.)

vVv Rapture said:
Let's say a brother and sister come together and both are Aa. When those two have children, the Punit Square would look like this:

A a
A AA Aa
a Aa aa

75% of the children would potentially have no signs of the recessive gene, but the unlucky 25% would be afflicted by this gene and, according to it, would die. This is just one generation of inbreeding and is completely possible.

Just wanted to point that out.

Let's consider two hypothetical situations: one in which the siblings have 4 offspring with each other, and one in which they have 4 offspring with separate mates, who are both AA. The average distribution of the recessive a trait would be:

Situation 1

25% Homozygous Dominant
50% Heterozygous
25% Homozygous Recessive

Overall, the trait appears 4 times (once in each heterozygote and twice in the recessive). The homozygous recessive is tragically killed before it can reproduce (or aborted, with the same result). So there are now two Heterozygotes in the population with the possibility of passing it on.

Situation 2

50% Homozygous Dominant
50% Heterozygous

All in all, there are still 4 recessive traits distributed among the 8 offspring, but now there are four heterozygotes capable of passing it on. So in the short term, the inbreeding causes 1 death, but there are now half as many recessive traits in the population. Better for the population, yes?

Ballistics · Oct 5, 2010

I guess its possible but I don't really think its probable, if you live in a populated area with lots of exposure then why are you so in love with your siblings.

Grandeza · Oct 5, 2010

Ballistics said:
I guess its possible but I don't really think its probable, if you live in a populated area with lots of exposure then why are you so in love with your siblings.

Honestly, this really isn't the thing the topic is meant to discuss. The topic at hand is to discuss the morality of incestuous relationships. Obviously it's not likely that you'll want to be in a relationship with your siblings, but it's still possible and it happens. It doesn't have anything to do with boredom or lack of exposure necessarily.

vVv Rapture · Oct 5, 2010

A1lion835 said:
And are you against gay marriage? Interracial marriage? Both of these were just as taboo as incest in large portions of the US in the past century or two, and there're still many individuals against both of them. So "socially taboo" isn't an acceptable reason at all.

I'll go into genetically hindering in response to your argument about it.

Naturally unnecessary - This also isn't a factor. It's not necessary for white people to have children; our civilization would survive plenty fine without it. Plus, the food that would go to feed the white children could instead be sent around to the starving populations of the world*. Not only that, but humans on a whole would be less susceptible to skin cancer, since the black population would increase! We'd also have fewer dumb racist jokes.

* (Feeding the starving populations around the world is not what I consider a good idea, but that's for another argument. Other Debaters who have read Ishmael, by Daniel Quinn, will understand where I'm coming from.)

The key word is were. They aren't now (even gay marriage, which isn't taboo, but just in the middle of a feud of two opposing parties; just a disagreement, big difference). We're talking about the present. What is socially taboo now is what matters and, in this case, incest is taboo and those two examples are not. The point still stands.

Also, I'm confused by your other argument. What do you mean by "necessary"?

Biologically, no, reproduction is not necessary to stay alive. But to continue the species, it sure as hell is. With that said, all humans then necessarily reproduce to make the next generation. White people do this for the same reason any other ethnicity does this (this is obviously not looking at accidental births, since accidental birth doesn't exist for any other animal, and other obvious reasons, etc) and this is because we're all humans. All of humanity does this, so all of each "race" (and race is just something we made up) does the same thing. White people don't make children to make more white people, they make children to make more humans.

Also, I won't go into those other...reasons, since those are either irrelevant, obvious, or not worth acknowledging.

Let's consider two hypothetical situations: one in which the siblings have 4 offspring with each other, and one in which they have 4 offspring with separate mates, who are both AA. The average distribution of the recessive a trait would be:

Situation 1

25% Homozygous Dominant
50% Heterozygous
25% Homozygous Recessive

Overall, the trait appears 4 times (once in each heterozygote and twice in the recessive). The homozygous recessive is tragically killed before it can reproduce (or aborted, with the same result). So there are now two Heterozygotes in the population with the possibility of passing it on.

I don't know why you would assume this homozygous recessive is "tragically killed." Seems a bit too convenient. You can't just bend the rules on an experiment to work into your favor.

With this situation, both those with Aa and aa would be able to reproduce. The "tragic death" is not, and should no, be a constant factor. Especially when most people who currently commit some sort of incest and actually produce offspring probably don't abort their children often or have plans to (assuming location, family background, religious background, financial situation applies).

Situation 2

50% Homozygous Dominant
50% Heterozygous

All in all, there are still 4 recessive traits distributed among the 8 offspring, but now there are four heterozygotes capable of passing it on. So in the short term, the inbreeding causes 1 death, but there are now half as many recessive traits in the population. Better for the population, yes?

Or, you can just not allow it at all and avoid the situation altogether.

A1lion835 · Oct 5, 2010

vVv Rapture said:
The key word is were. They aren't now (even gay marriage, which isn't taboo, but just in the middle of a feud of two opposing parties; just a disagreement, big difference). We're talking about the present. What is socially taboo now is what matters and, in this case, incest is taboo and those two examples are not. The point still stands.

The point I'm making here is that, 150 years ago, people would say "no, you can't have an interracial marriage, that's not socially acceptable," and looking back, we can say "Oh, that was racist, times have changed, that's no longer taboo. That was wrong." So when debating with current taboo (which is pretty much useless anyways, as I pointed out in the OP), you need to keep in mind that 150 years from now, people could be saying "Oh, those horrible people forbid inbreeding, that was morally wrong of them."

vVv Rapture said:
Also, I'm confused by your other argument. What do you mean by "necessary"?

Biologically, no, reproduction is not necessary to stay alive. But to continue the species, it sure as hell is. With that said, all humans then necessarily reproduce to make the next generation. White people do this for the same reason any other ethnicity does this (this is obviously not looking at accidental births, since accidental birth doesn't exist for any other animal, and other obvious reasons, etc) and this is because we're all humans. All of humanity does this, so all of each "race" (and race is just something we made up) does the same thing. White people don't make children to make more white people, they make children to make more humans.

Also, I won't go into those other...reasons, since those are either irrelevant, obvious, or not worth acknowledging.

By necessary, I mean the same thing as (I thought) you meant: you said that brothers and sisters didn't need to reproduce, which, while not really addressing the issue of whether or not incest is morally correct, I decided to tackle. I used the same logic ("this group of people doesn't need to reproduce with each other") and applied it to the lighter-skinned people of the world, pointing out several benefits.

I'd appreciate if you pointed out which of the reasons were irrelevant so I could point out that the paragraph was largely sarcastic.

vVv Rapture said:
I don't know why you would assume this homozygous recessive is "tragically killed." Seems a bit too convenient. You can't just bend the rules on an experiment to work into your favor.

It seemed that your description of the recessive gene was that it killed the offspring early, which is why I said it was "tragically killed." I'm not saying some guy walked up and shot him, I'm saying his genetic disease killed him sometime near to birth.

With this situation, both those with Aa and aa would be able to reproduce. The "tragic death" is not, and should no, be a constant factor.

Either redefine your recessive trait to not be fatal at ages before offspring are reproduced, or accept the death as a result of the trait.

vVv Rapture said:
Especially when most people who currently commit some sort of incest and actually produce offspring probably don't abort their children often or have plans to (assuming location, family background, religious background, financial situation applies).

So tell me, what statistics do you know about people who commit incest? I'm not necessarily challenging the factual accuracy of your claim, but I'm wondering where your references are. The abortion point was that, if the couple knew their child would have terrible mutations, abortion could be an option.

vVv Rapture said:
Or, you can just not allow it at all and avoid the situation altogether.

"Or, instead of debating about something, we could just pretend that I already won."

El Nino · Oct 5, 2010

Ballistics said:
I guess its possible but I don't really think its probable, if you live in a populated area with lots of exposure then why are you so in love with your siblings.

It has happened by accident. Usually, non-abusive cases of incest occur when two people who don't know they are related meet.

vVv Rapture said:
Biologically, no, reproduction is not necessary to stay alive. But to continue the species, it sure as hell is. With that said, all humans then necessarily reproduce to make the next generation.

Successful reproduction in order to sustain the species comes up in the debate on the acceptance of homosexuality as well. If an incestuous couple does not have children, then is this union biologically any worse or better for the human population than a homosexual union, or a union of infertile individuals?

On that note, how do you guys feel about people with genetic predispositions to certain diseases having kids?

Or, what if we had gene therapy available at affordable cost to almost everyone that could eliminate the detrimental effects of certain recessive traits that can occur through inbreeding? Would that eliminate the need to maintain this taboo against incest?

ballin4life · Oct 6, 2010

I don't have a problem with voluntary relationships. As someone pointed out, it's similar to homosexual relationships, in that people mainly dislike them because they are not the "usual" case.

I will say that I would find it strange, or maybe distasteful, but definitely not morally wrong.

vVv Rapture · Oct 6, 2010

A1lion835 said:
The point I'm making here is that, 150 years ago, people would say "no, you can't have an interracial marriage, that's not socially acceptable," and looking back, we can say "Oh, that was racist, times have changed, that's no longer taboo. That was wrong." So when debating with current taboo (which is pretty much useless anyways, as I pointed out in the OP), you need to keep in mind that 150 years from now, people could be saying "Oh, those horrible people forbid inbreeding, that was morally wrong of them."

Alright. Not much to argue there...as that's pretty obvious.

By necessary, I mean the same thing as (I thought) you meant: you said that brothers and sisters didn't need to reproduce, which, while not really addressing the issue of whether or not incest is morally correct, I decided to tackle. I used the same logic ("this group of people doesn't need to reproduce with each other") and applied it to the lighter-skinned people of the world, pointing out several benefits.

I'd appreciate if you pointed out which of the reasons were irrelevant so I could point out that the paragraph was largely sarcastic.

I was aware of it being sarcastic, which is why I didn't comment on it (ie, there being less racist jokes with less/no more white people). Unless you wanted me to argue about that. xD

It seemed that your description of the recessive gene was that it killed the offspring early, which is why I said it was "tragically killed." I'm not saying some guy walked up and shot him, I'm saying his genetic disease killed him sometime near to birth.

Oh, alright. My apologies, I completely forgot about that. Yes, that'd be fine then.

So tell me, what statistics do you know about people who commit incest? I'm not necessarily challenging the factual accuracy of your claim, but I'm wondering where your references are. The abortion point was that, if the couple knew their child would have terrible mutations, abortion could be an option.

I'd have to look them up, I can if you'd like me to. And yes, abortion would be an option, not not necessarily always picked as one.

"Or, instead of debating about something, we could just pretend that I already won."

I was just reaffirming my stance on the issue when I said that.

El Nino-

Successful reproduction in order to sustain the species comes up in the debate on the acceptance of homosexuality as well. If an incestuous couple does not have children, then is this union biologically any worse or better for the human population than a homosexual union, or a union of infertile individuals?

It's an odd debate. Naturally, we reproduce to keep the species alive. However, it seems like humanity has almost fallen outside of the realm of many natural limits as of late. Animals instinctively mate to make the next generation, they don't do it out of choice, nor are they aware of their species' actual numbers. Pests, which can have numbers up into the hundreds of thousands, still reproduce and have no idea how much of themselves already exist.

On the other hand, humans are fully aware...well, educated ones, that is. Even with that said, reproduction is not an instinct anymore. We do it out of choice (this is why you see families with no offspring or offspring in different numbers [1, 2, 3 or 19 like those people on TLC]).

So, it's hard to answer that. Biologically, yes, having a relationship that cannot produce offspring is bad, because reproduction is there to continue the next generation. But, then someone could make the point that there are too many humans on the planet already and that it's better to not reproduce as much or at all.

Unfortunately, us humans fall outside of the norm. It's really hard to show what's natural and what isn't because we've taken so much control over ourselves that we've completely bent the rules on many of what limits other creatures.

Namaste · Oct 6, 2010

junkimchi said:
we aren't dolphins.

nor are we peas that can self fertilize.

Bull****! Prove these claims sir

A1lion835 · Oct 6, 2010

El Nino said:
It has happened by accident. Usually, non-abusive cases of incest occur when two people who don't know they're related meet.

This is very true. I believe there's a brother-sister couple who met like this debating against incest laws in Germany.

El Nino]Successful reproduction in order to sustain the species comes up in the debate on the acceptance of homosexuality as well. If an incestuous couple does not have children said:
I'd have to look them up, I can if you'd like me to. And yes, abortion would be an option, not not necessarily always picked as one.

I agree that abortion, controversial on its own, probably isn't the primary choice here.

El Nino · Oct 6, 2010

A1lion835 said:
So when we have starving children in Africa, instead of saying "Well, we've got over-population, it's best to let some humans die," we say "Oh no, we can't let them die, we need to make lots of food," which in turn enables the human species to grow more.

This is just an aside, but I think that the "starving children in Africa" concept is an ethnocentric stereotype.

A1lion835 · Oct 6, 2010

El Nino said:
This is just an aside, but I think that the "starving children in Africa" concept is an ethnocentric stereotype.

I'm not really well-informed on the matter, but whether or not you're right (it seems likely that you are, since you obviously know what you're talking about) doesn't really affect my argument that refusing to let any humans die "prematurely" is a good idea.

El Nino · Oct 7, 2010

A1lion835 said:
I'm not really well-informed on the matter, but whether or not you're right (it seems likely that you are, since you obviously know what you're talking about) doesn't really affect my argument that refusing to let any humans die "prematurely" is a good idea.

You're right; it doesn't affect your argument. It was just an aside.

I think we can agree that limiting population via family planning is much more humane than allowing already living people to suffer and die.

But to keep the debate rolling:

All in all, there are still 4 recessive traits distributed among the 8 offspring, but now there are four heterozygotes capable of passing it on. So in the short term, the inbreeding causes 1 death, but there are now half as many recessive traits in the population. Better for the population, yes?

Recessive traits don't always cause immediate death, but if they cause suffering in the child, that would be one argument against incest. Or, at least against incestuous relationships intending to give birth to a child.

Furthermore, recessive alleles can stay in a population in low frequencies for various reasons. Incest isn't a reliable way to "breed out" a recessive gene. And even if it were, it probably wouldn't be humane, for obvious reasons.

Aside from genetics, there's the psychological factor. Any thoughts about whether or not it's possible for a person to be involved in a consentual incestuous relationship WITHOUT experiencing or having experienced psychological trauma or abuse?

Pragmatic · Oct 8, 2010

vVv Rapture said:
I'll first put it on the table that I'm against incest and any marriage based on it. Many reasons have already been stated (social taboo, genetically hindering, naturally unnecessary, etc).

However, on this point, this isn't necessarily true. Let me give an example:

A - Gene, harmless, non-fatal, dominant
a - Gene, harmful, fatal, recessive

Let's say a brother and sister come together and both are Aa. When those two have children, the Punit Square would look like this:

A a
A AA Aa
a Aa aa

75% of the children would potentially have no signs of the recessive gene, but the unlucky 25% would be afflicted by this gene and, according to it, would die. This is just one generation of inbreeding and is completely possible.

Just wanted to point that out.

Excellent point.

Alleles are heavily dependent on determining the genetic offspring of a child.

If two parents engage in an incestuous relationship, it increases the chance of said child being born with a wide range of neurological and biological difficulties.

It's associated with stigma for a reason; many of the effects are simply negative. No, I'm not talking about morals, I'm proving this point with hard, scientific fact.

Morality is subjective and therefore shouldn't be issued in this debate. However, the genetic probabilities of inheriting recessive and damaging genes, is still present.

Why would brother and sister have sex in this current age anyways? Not only is stigma associated with this, modernization has occured, and transportation links have increased and improved as a result. Meaning they'll come across a wide range of potential mates, all from different cultural and national backgrounds. Previously, one large family lived on a farm, and couldn't access a large or moderate population for breeding, there were no mates anywhere close by. So, a last resort was proposed.

So, essentially speaking, brother and sister wouldn't -need- to mate, and since genetic variability exists, they also wouldn't normally be attracted to each other for sexual reproduction in the first place.

Sucumbio · Oct 8, 2010

Some incest is okay, I guess. Like first cousins, I think I'd draw the line there though... closer relationships ie father/daughter, mother/son, brother/sister, aunt/uncle/niece/nephew, these seem, well... most people aren't attracted to their own family members, so I guess it just depends on the person. If it feel "right" for some strange reason, go for it? This is a strange topic, why does this topic surface every now and then, I wonder...

a couple interesting reads:

You Are Sexually Attracted to Your Parents, and Yourself

Forbidden love: Facts about genetic sexual attraction

Now I remember which topic it was recently that was about this. It was in the Pool Room iirc, regarding a grandmother and her grandson having a child.

gm jack · Oct 9, 2010

Morally, you have to consider that incestuous relationships may not be voluntary for one or both parties, or the parties may be brainwashed by slightly crazy parents. If you open up the flood gates for close relative to marry, you then get the the very weird grounds of parents marrying children, which I highly doubt would be fully consensual. However, even at a subconscious level, we try to select a genetically different mate, so reducing the chance of this happening.

http://www.youtube.com/watch?v=KHp_Y7wCRaw

This guy is the head of my course, and knows his stuff. He says near the end that women tended to prefer the smell of sweat from men who were more genetically different.

Biologically, humans are not adapted for inbreeding. Charles Darwin married his first cousin, and has written that he believes that to have been the reason his children were sickly.

Essentially, we are fairly hetrozygotic for most variable genes. Therefore, a large number of these are likely to be detrimental, but covered by the effects of being paired with a correctly functioning gene. With inbreeding, it is likely that several of these detrimental genes will become homozygous at the locus, resulting in a weaker child.

Now over many generations, this inbreeding depression lessens, as the worst genes get removed from the gene pool. This is how tribes of people on islands etc who are very isolated have survived. But for most of us, inbreeding is incredibly likely to result in a child who is at the least sickly, and at the worst at a much higher chance of having a serious genetic defect.

A1lion835 · Oct 10, 2010

Pragmatic said:
Excellent point.

Regardless of how excellent it is, I dealt with it in an earlier post.

Pragmatic said:
Alleles are heavily dependent on determining the genetic offspring of a child.

If two parents engage in an incestuous relationship, it increases the chance of said child being born with a wide range of neurological and biological difficulties.

Wikipedia said:
Inbreeding leads to a higher proportion of congenital birth defects through an increase in the frequency of homozygotes. The effects of this can diverge - recessive genes that produce birth defects could become more frequent, resulting in a higher rate potential of these defects while genes that do not code for birth defects can become increased within a population.

tl;dr version: There could be mutant babies with bad recessive genes, or super-babies with good recessive genes.

Pragmatic said:
It's associated with stigma for a reason; many of the effects are simply negative. No, I'm not talking about morals, I'm proving this point with hard, scientific fact.

Again, the "super babies" point from my last post.

Wikipedia]The overall consequences of this divergence depends in part on the size of the population. In small populations said:
Morally, you have to consider that incestuous relationships may not be voluntary for one or both parties, or the parties may be brainwashed by slightly crazy parents. If you open up the flood gates for close relative to marry, you then get the the very weird grounds of parents marrying children, which I highly doubt would be fully consensual. However, even at a subconscious level, we try to select a genetically different mate, so reducing the chance of this happening.

I find it hard to believe that in an age where arranged marriages are hardly practiced (and if they are, it's probably concentrated in highly religious groups, whose scriptures usually forbid incest), that that would happen.

I'd agree that non-consensual incest is bad.

The likelihood isn't really relevant.

gm jack said:
http://www.youtube.com/watch?v=KHp_Y7wCRaw

This guy is the head of my course, and knows his stuff. He says near the end that women tended to prefer the smell of sweat from men who were more genetically different.

Not the subject of the argument.

gm jack said:
Biologically, humans are not adapted for inbreeding. Charles Darwin married his first cousin, and has written that he believes that to have been the reason his children were sickly.

This is an example of recessive genes going bad. There may have been other factors which caused it (not to disregard the argument at all, just saying either more data or more research into Darwin's family is needed).

And the end result of his children being sickly is that those genes were eliminated from the population (if they died before reproducing). Otherwise, the genes would be quickly weeded out anyway.

gm jack said:
Essentially, we are fairly heterozygotic for most variable genes. Therefore, a large number of these are likely to be detrimental, but covered by the effects of being paired with a correctly functioning gene. With inbreeding, it is likely that several of these detrimental genes will become homozygous at the locus, resulting in a weaker child.

Maybe it's because I haven't taken high-level science courses, but I have no idea where this is coming from. Could you elaborate?

gm jack said:
Now over many generations, this inbreeding depression lessens, as the worst genes get removed from the gene pool. This is how tribes of people on islands etc who are very isolated have survived. But for most of us, inbreeding is incredibly likely to result in a child who is at the least sickly, and at the worst at a much higher chance of having a serious genetic defect.

As I stated earlier, recessive does not imply bad, and the increase in mortality rate between cousin incest children is only 4.4% . Otherwise, I agree with the quote.

Pragmatic · Oct 11, 2010

If society associates a certain trend or concept with stigma, it's negative for a reason. Homosexuality is an exception, but then there's the point that said couples don't reproduce naturally. [Generally]

However, that's another debate. But, you seem to stress the point inbreeding doesn't increase the chances of offspring inheriting genetic disorders?

Of course there are mere exceptions, but you're forgetting babies can still contain the genetic disorders as "carriers", which they can easily pass off to their future offspring as recessive genes accumulate.

Super babies from recessive genes? I'm not following, not probable.

*edit* Morality and anything expressing pure personal opinion is opening a can of worms.

1048576 · Oct 11, 2010

'It's negative for a reason' might be a good heuristic, but it's an appeal to authority (society) / bandwagon fallacy, so it really holds no merit in an argument. To convince an undecided onlooker, you should try to cite the reason for each individual stigma.

Pragmatic · Oct 11, 2010

1048576 said:
'It's negative for a reason' might be a good heuristic, but it's an appeal to authority (society) / bandwagon fallacy, so it really holds no merit in an argument. To convince an undecided onlooker, you should try to cite the reason for each individual stigma.

Fair enough, I'll list the main reasons.

Incestuous relationships aren't a likelihood in the first place, due to genetic variability. Meaning, biologically, we'll opt to find the most genetically different mate possible to ensure a healthy set of sufficient chromosomes. "Exotic" women, one of different ethnicities, are prime candidates and this is why they're labelled as such. The possibility of mating with one might not be high, but the factor still exists.

Onto my second, more obvious point. Inbreeding does increase the chances of developing genetic disorders such as Tay-Sachs Syndrome, due to recessive genes accumulating until those alleles become recessive-dominant. If both parents originally had defective genes, even if they were merely carriers, the offspring can still inherit them, and the percentages are therefore increased. [If the alleles are heterozygous, the recessive genes practically become null and void, but they can still be carriers. If their homozygous for the defective trend, due to inbreeding when the chances are considerably higher, you develop harmful genetic disorders.]

That was a lot longer than I intended.

Refer to Rapture's mathematical formula for further clarity.

El Nino · Oct 12, 2010

gm jack said:
Morally, you have to consider that incestuous relationships may not be voluntary for one or both parties, or the parties may be brainwashed by slightly crazy parents.

An involuntary sexual relationship is always a problem, regardless of whether it is incestuous or not.

Biologically, humans are not adapted for inbreeding.

Humans are adapted to go either way, actually. Royal families have been known to practice inbreeding (sometimes to detrimental effect). But the practice served the purpose in society of granting legitimacy to a political ruler. For the rest of the population, mate selection generally favors both difference and similarity to family members.

Charles Darwin married his first cousin, and has written that he believes that to have been the reason his children were sickly.

Ethics is a matter for society to consider. Apart from his children, was anyone else in society harmed by his marriage?

If incestuous couples opted not to have biological children of their own, would those of you arguing against incest still hold objections?

A1lion835 said:
And the end result of his children being sickly is that those genes were eliminated from the population (if they died before reproducing). Otherwise, the genes would be quickly weeded out anyway.

To play devil's advocate for a second, if those children suffered considerably due to a genetic illness, would that not be sufficient cause for society to prohibit (or at least discourage) incest?

Maybe it's because I haven't taken high-level science courses, but I have no idea where this is coming from. Could you elaborate?

Genes come in pairs because we get one from each parent. If one parent is recessive (a) for a trait, and another parent is dominant (A) for the same trait, the child is Aa. The dominant trait (A) is the one that gets expressed. The recessive trait (a) is suppressed. An Aa child is a carrier for the recessive (a) gene.

Generally, Aa is going to be more common than AA or aa. The point argued here is that since most people are Aa, incest would lead to a higher frequency of aa.

Pragmatic said:
biologically, we'll opt to find the most genetically different mate possible to ensure a healthy set of sufficient chromosomes.

As stated above, I believe the trend in mate selection is towards a median between similarities and differences. Keep in mind that foreigners would have posed a risk in ancient times due to the possibility of being exposed to a disease that you didn't have immunity against.

The possibility of mating with one might not be high, but the factor still exists.

Lulz. But that's another thing to consider. If the chances of mating with a foreigner is low, then it would be disadvantageous to try, and those who chose to pursue potential mates with whom they have more in common would have a higher success rate.

Pragmatic · Oct 12, 2010

El Nino said:
Lulz. But that's another thing to consider. If the chances of mating with a foreigner is low, then it would be disadvantageous to try, and those who chose to pursue potential mates with whom they have more in common would have a higher success rate.

You misinterpreted what I said.

The primitive instinct to mate with the most genetically different partners still exists, as it's built into our biological desires, but when we realize the chances of this are low, we essentially settle for less, a fool-proof plan.

In strip clubs and the adult movie industry, "exotic" women tend to be more favourable on a large scale, although exceptions obviously exist. The same concept applies with this as it does to genetic variability.

El Nino · Oct 12, 2010

Pragmatic said:
The primitive instinct to mate with the most genetically different partners still exists, as it's built into our biological desires, but when we realize the chances of this are low, we essentially settle for less, a fool-proof plan.

Well, no plan is completely fool-proof (especially when it comes to mating). But can you present the science behind the idea that the mating instinct in humans favors the "most genetically different" partners?

In strip clubs and the adult movie industry, "exotic" women tend to be more favourable on a large scale, although exceptions obviously exist. The same concept applies with this as it does to genetic variability.

Sure, but are the people who buy the most adult films getting laid? And are their preferences representative of their own sexual encounters?

Strip clubs and adult films play to fetishes, but that doesn't necessarily result in successful mating. People watch movies and go to strip clubs to get sexual relief. Successful mating involves settling down and having kids. Usually people get along better with others in relationships when they have something in common, and I wouldn't call that "settling" for less. I just think that fetishization can only take you so far.

gm jack · Oct 12, 2010

A1lion835 said:
I find it hard to believe that in an age where arranged marriages are hardly practiced (and if they are, it's probably concentrated in highly religious groups, whose scriptures usually forbid incest), that that would happen.

I'd agree that non-consensual incest is bad.

The likelihood isn't really relevant.

Arranged marriages happen in a lot of cultures. One of by best friends (who is Indian) has parents who had an arranged marriage, and it is not a rare occurance, even though they are leading away from it.

This is an example of recessive genes going bad. There may have been other factors which caused it (not to disregard the argument at all, just saying either more data or more research into Darwin's family is needed).

And the end result of his children being sickly is that those genes were eliminated from the population (if they died before reproducing). Otherwise, the genes would be quickly weeded out anyway.

Genetics is far more complex than a simple dominance/recessive relationship. Even so, if in his case there were other factors, several of the old royal families in europe have died out aa a result of inbreeding.

http://en.wikipedia.org/wiki/Charles_II_of_Spain

It is also a proven effect in many animal species, and breeders go to great lengths to avoid inbreeding. Failure often results in genetic defects, which is why many dog breeds have problems associated with them.

Maybe it's because I haven't taken high-level science courses, but I have no idea where this is coming from. Could you elaborate?

Essentially, if we breed around, we tend to have different genes at positions which are commonly variable on each set of genetic material (we all have two, one from each parent). If we tend to have different alleles at many loci, it means that we in essence are more "well rounded", as we have a minimal chance of any detrimental gene being allowed to determine the characteristics of the animal to a great extent. However, inbreeding reduces some of this variety. While indeed some good genes may become duplicated, it also means that rarer detrimental genes (which family members are more likely to share) have a high chance of being inherited from both parents, resulting in genetic diseases in the child.

As I stated earlier, recessive does not imply bad, and the increase in mortality rate between cousin incest children is only 4.4% . Otherwise, I agree with the quote.[/QUOTE]

Recessive is often bad because it is often a mutation that inactivates a gene. It is recessive because if it is not functional, then the other can take over, and the faulty gene needs to be present twice for none of it's product to be produced. If there was a gene for it, it was probably necessary.

Pragmatic · Oct 12, 2010

El Nino said:
Well, no plan is completely fool-proof (especially when it comes to mating). But can you present the science behind the idea that the mating instinct in humans favors the "most genetically different" partners?

Genetic variability. Why do you think bacterium cells like to find a wide range of hosts?

By mating with polar opposites of the genetic spectrum, it produces chromosomes and cellular systems that due to their inherent properties, can withstand harmful diseases because of the different genetic coding already enabled. By adapting to a wide series of genes, they become stronger.

Essentially, this is saying offspring with various genetic traits are going to be healthier. I'm not wording this very well, sorry.

But I hope the concept I'm trying to implement is understandable.

Sure, but are the people who buy the most adult films getting laid? And are their preferences representative of their own sexual encounters?

Strip clubs and adult films play to fetishes, but that doesn't necessarily result in successful mating. People watch movies and go to strip clubs to get sexual relief. Successful mating involves settling down and having kids. Usually people get along better with others in relationships when they have something in common, and I wouldn't call that "settling" for less. I just think that fetishization can only take you so far.

Fetishization really has nothing to do with primitive sex drives, they are not relevant whatsoever. I'm also not attempting to prove or disprove any theories with fetishization, as it's not important.

But even so, using your examples, I can also argue that people who get sexual relief are more prone [especially strip clubs, pornography in particular is for an immediate ejaculation] for exotic, more genetically different women. The drive is still there because of genetic variability, which in turn, allows cells and bacterium to survive harmful outside forces because of the ability to adapt. So biologically, our inherent primitive nature is giving us the different tools to survive and evolve.

Upon failing that, we will find a mate with slightly similar genetic traits, as it's still reproduction.

A1lion835 · Oct 14, 2010

I can recognize when I'm losing, and I'm ready to mostly accept defeat -- for now. I'd like to maintain my point that inbreeding isn't always bad for the offspring, but it often is. In some populations, inbreeding is helpful. Which brings me to my last point about this debate.

If incest does result in bad genes, is that enough to forbid incestuous unions? Do humans really have the right to say "Science says you won't be doing the best thing for the population, so your relationship isn't allowed?" And if so, couldn't that be largely extended to the LGBT movement?

El Nino · Oct 15, 2010

Pragmatic said:
Genetic variability. Why do you think bacterium cells like to find a wide range of hosts?

By mating with polar opposites of the genetic spectrum, it produces chromosomes and cellular systems that due to their inherent properties, can withstand harmful diseases because of the different genetic coding already enabled. By adapting to a wide series of genes, they become stronger.

I think I know what you're saying, but just to help you out with the wording there: Mating doesn't "produce" chromosomes, it "combines" chromosomes. "Adaptation" is usually used in reference to the outer environment, not to genes themselves. As in, genotype AA allows an individual to succeed in the environment, and as AA proliferates, the population will become adapted to that environment.

So biologically, our inherent primitive nature is giving us the different tools to survive and evolve.

Upon failing that, we will find a mate with slightly similar genetic traits, as it's still reproduction.

We are disagreeing on where the attraction to difference comes from. The literature suggests that it is not 100% black and white for all members of a population. I don't think a genetic cause for attraction has been found either. It's just been observed that some members of a population will be attracted to mates who are different, while others are attracted to mates who are similar. Even if it is a genetic trait, that still doesn't mean that everyone has it. And unless there is evidence that attraction to difference is heritable, there's nothing to rule out the possibility that attraction to the "exotic" is a cultural artifact. Humans are subject to social conditioning when it comes to sex and attraction, just as we are subject to socioeconomic concerns and psychological factors that may be independent of genetics.

A1lion835 said:
I can recognize when I'm losing, and I'm ready to mostly accept defeat -- for now.

I'm not sure you're losing, but if you are, it's only because you chose to argue in favor of inbreeding. Another option for you could have been to argue in favor of incest but at the same time promote educating people about the dangers of inbreeding to encourage incestuous couples to seek adoption rather than have their own children. You could also have brought up advances in modern medicine in the field of genetics. What if in the future we have the technology to "repair" the ill effects of inbreeding? Would it matter if reproducing couples are related or not, at that point?

A1lion835 · Oct 15, 2010

Thanks for the backing El Nino, and you make some really good points. I'll have to think about this for a bit before I reformat my goal and respond.

Pragmatic · Oct 15, 2010

@ Nino:

Makes sense. Thanks for the wording correction, my mistake.

We are disagreeing on the semantics involved, but agreeing on the main points?

El Nino · Oct 16, 2010

Pragmatic said:
We are disagreeing on the semantics involved, but agreeing on the main points?

Seems about right.

I didn't expect an incest thread to be all up in the biology of it. I was expecting more about the psychology or something.

#HBC | Acrostic · Oct 22, 2010

Pragmatic said:
Inbreeding does increase the chances of developing genetic disorders such as Tay-Sachs Syndrome, due to recessive genes accumulating until those alleles become recessive-dominant. If both parents originally had defective genes, even if they were merely carriers, the offspring can still inherit them, and the percentages are therefore increased. If the alleles are heterozygous, the recessive genes practically become null and void, but they can still be carriers. If their homozygous for the defective trend, due to inbreeding when the chances are considerably higher, you develop harmful genetic disorders.

The post you've written insinuates that there are only autosomal recessive diseases, even though inbreeding does increase the chances of developing genetic disorders. Autosomal recessive genes make a convincing argument for avoiding inbreeding, yet this causes one to extend the genetic question to whether or not individuals who contain mutated and/or dysfunctional genes in general should be able to reproduce and be able to mate with other individuals who may have other genomic disorders. Especially when these traits might be autosomal dominant, Y-linked disorders, and other possibilities that have the possibility of resulting in malignant diseases upon the reception of only one allele from a given pair. This poses an interesting debate as at one end of the spectrum the premise you are advocating is a smart decision for the welfare of possible offspring, on the other end some individuals might claim that the underlying premise is a diluted application of Eugenics. Interesting post.

Pragmatic · Oct 23, 2010

Acrostic said:
The post you've written insinuates that there are only autosomal recessive diseases, even though inbreeding does increase the chances of developing genetic disorders. Autosomal recessive genes make a convincing argument for avoiding inbreeding, yet this causes one to extend the genetic question to whether or not individuals who contain mutated and/or dysfunctional genes in general should be able to reproduce and be able to mate with other individuals who may have other genomic disorders. Especially when these traits might be autosomal dominant, Y-linked disorders, and other possibilities that have the possibility of resulting in malignant diseases upon the reception of only one allele from a given pair. This poses an interesting debate as at one end of the spectrum the premise you are advocating is a smart decision for the welfare of possible offspring, on the other end some individuals might claim that the underlying premise is a diluted application of Eugenics. Interesting post.

Well, the examples I provided are actually X- linked chromosomal disorders, in which the defective X and Y chromosomes are subsequently accumulated in an offspring. Since both parents have X chromosomes, and the father has a Y, gender plays a large role in determining whether a child will have a genetic disorder.

Since the father only has 1 Y, if that particular allele is affected, the male child will inherit it regardless. In the case with a female, the father's X allele may be affected, but the mother's healthy, dominant X chromosome will have considerable more priority, resulting in only a carrier.

Even so, the risks are still present and never go away.

The same is applicable with autosomal genes, but there are minor semantics involved.

Nonetheless, the question of morality is a good one, because scientifically, we have considerable proof that inbreeding is harmful, but should we prohibit genetically ill individuals from mating with someone they love? Depends, I'm not in a position to claim whether that's correct.

On a scientific viewpoint, however, the answer is a lot more concrete.

#HBC | Acrostic · Oct 23, 2010

Point taken. I glanced at El Nino and GM Jack's explanation which primarily seemed to focus on the inheritance of autosomal traits and my comment followed pursuit. To take GM Jack's point further in which he states that inheritance goes beyond a simple dominant/recessive relationship, there are number of traits that are difficult to link to parental genetics. In the realm of sex-linked diseases, take Klinefelter's syndrome in which a human male contains the following sex chromosomes: XXY. Even though sex-linked, it is a trisomic aneuploid which is caused by nondisjunction at the second meiotic division. The result of this cross is often the result of a weakened mitotic checkpoint that prematurely initiates meiosis.

A question arises for factors that can induce chromosome mutations. Colchicine is a chemical reagent that inhibits chromosome segregation and cell division, therefore leading to the mitotic formation of a tetraploid cell, instead of two diploid cells. The fact that factors outside of genes themselves, such as environmental factors and chemical toxins could induce mishaps in chromosome pairing, division, and formation leads some skepticism to placing faith in a genetics based measure to ensure that children are successfully reproduced. Of course, the current discussion has ignored the underlying truth, in that genetic factors are transcribed and translated to form proteins that function in biochemical pathways, as enzymes, as polymerase, as helicase, and as telomerase (so on and so forth). We also have not reviewed cases of incomplete dominance, codominance, pleiotropic allelic factors, and perhaps even more in-depth matters of molecular genetics.

The scientific viewpoint itself can get fairly convoluted as traits are often a phenotype that has been expressed from exons in a given genotype that theoretically encodes for a large quantity of factors to ultimately produce the visible phenotype. Mitigating those factors appropriately is difficult to control and difficult to predict.

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