Is homosexuality innate?

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Is homosexuality innate?

Post #1

Post by Haven »

Debate Topic
Is homosexuality innate?
Subtitle: is there any scientific justification?


Debate Terms
1. All arguments should be based on scientific evidence or studies that have been consistently and independently replicated. Absolutely no comments about politics, religion, and motives of debaters.

Due to many problems in the past forums, I request that otseng (forum site adminstrator) agree to enforce the part in the 2nd sentence about no politics, religion, and motives being discussed in the debate. Continued violation (more than once) of debate term #1, 2nd sentence, can result in the non-guilty party requesting to have the entire head-to-head debate thread deleted.

2. You must cite the source and relevant section (if its a long book or article) for all scientific sources.

3. No proselytizing or preaching. Regardless of your personal beliefs about LGBT identities (sinful, fabulous, etc.), stick to the evidence at hand. Blanket statements (e.g., "homosexuality is a sin!") are grounds for immediate forfeiture of the debate and closure of the thread.

4. No use of terms that are considered offensive to non-heterosexual people (offensive terms such as homosexual, transexual, etc).

5. This debate will last for 16 days the most, starting August 16, 2015 and ending on August 31, the latest, unless agreed upon by both of us in advance. Haven and I will have a maximum of 3 days at most to post a response to each others post which will put the debate on schedule to end on August 31, or sooner.

6. No side threads or comments should be made or created anywhere on the forum that's about our head-to-head until after the debate ends.


Debate format:
Post #1: Haven's opening argument
Post #2: OpenYourEyes intro/rebuttal
Post #3: Haven's rebuttal
Post #4: OpenYourEyes rebuttal
Post #5: Haven's closing argument
Post #6: OpenYourEyes closing argument

* Closing arguments can not contain any new evidence and/or arguments based on a topic or matter that was not covered earlier in the debate.
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Post #2

Post by Haven »

Well, I suppose this won't happen now since my opponent was banned. Mods, please lock this thread.
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Post #3

Post by Wootah »

Haven wrote: Well, I suppose this won't happen now since my opponent was banned. Mods, please lock this thread.

Moderator Comment

The ban has been lifted.

Please review the Rules.


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Post #4

Post by Haven »

Ok, I'll make my first post today.
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Post #5

Post by OpenYourEyes »

Haven,

We are behind schedule and yeah my being banned for no reason does not help a bit. I need an opening argument from you to refute because today starts the day that i was supposed to be working on my refutation of your first post. Without that first post, it's eatting into my time which was pre-planned so that the debate ends on Aug. 31, with each of us getting up to 3 days to respond to each other's post.
Last edited by OpenYourEyes on Mon Aug 17, 2015 12:55 pm, edited 2 times in total.

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Post #6

Post by Haven »

[Replying to post 5 by OpenYourEyes]

I'll have it by 6 MST
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Is homosexuality innate?

Post #7

Post by Haven »

First of all, I'd like to thank my opponent for graciously offering to proceed with this debate. The question we'll be discussing is "is homosexuality innate?" While this question seems straightforward, it's actually a bit more complex than it looks.

To have a clear debate, we must first define what is meant by "homosexuality" and "innate." For the purposes of this discussion, the terms are defined as follows:

1. Homosexuality is defined as the exclusive attraction to members of the same gender. It has nothing to do with sexual activity, only attraction.

2. Innate is defined as determined by genetics, hormones, and/or brain structure before birth or during early development. It doesn't necessarily mean that the trait (in this case, homosexuality) is present at birth, but that it will develop at some point during the life course due to the aforementioned factors. If something is innate, it is not chosen or determined by environmental factors.

So, back to the question, is homosexuality innate? It's my position that the evidence clearly suggests "yes," while my opponent (OpenYourEyes) believes "no."

Before getting to the actual evidence, I just wanted to clear up one thing first:

The goal of this debate is to discover the most likely explanation, not to gain absolute certainty. As with all things in science, nothing can be known with absolute certainty, and so asking for such proof is an unreasonable request. My aim here is to advance the position that homosexuality is as likely to be innate as, for example, influenza is likely to be caused by a virus. This is a very high level of certitude, of course, but it's not absolute.

Now, on to the evidence. For this, I will present five recent studies, each of which present strong evidence that homosexuality is innate in both women and men:

1. This 2012 study links homosexuality (in both lesbians and gay men) to epigenetic factors: http://www.jstor.org/stable/10.1086/668167 . Specifically, it states:
[color=green]Rice, Friberg, & Gavrilets 2012[/color] wrote:We show that an unappreciated feature of this process is reduced androgen sensitivity in XX fetuses and enhanced sensitivity in XY fetuses, and that this difference is most feasibly caused by numerous sex-specific epigenetic modifications (“epi-marks�) originating in embryonic stem cells. These epi-marks buffer XX fetuses from masculinization due to excess fetal androgen exposure and similarly buffer XY fetuses from androgen underexposure. Extant data indicates that individual epi-marks influence some but not other sexually dimorphic traits, vary in strength across individuals, and are produced during ontogeny and erased between generations. Those that escape erasure will steer development of the sexual phenotypes they influence in a gonad-discordant direction in opposite sex offspring, mosaically feminizing XY offspring and masculinizing XX offspring. Such sex-specific epi-marks are sexually antagonistic (SA-epi-marks) because they canalize sexual development in the parent that produced them, but contribute to gonad-trait discordances in opposite-sex offspring when unerased. In this model, homosexuality occurs when stronger-than-average SA-epi-marks (influencing sexual preference) from an opposite-sex parent escape erasure and are then paired with a weaker-than-average de novo sex-specific epi-marks produced in opposite-sex offspring. Our model predicts that homosexuality is part of a wider phenomenon in which recently evolved androgen-influenced traits commonly display gonad-trait discordances at substantial frequency, and that the molecular feature underlying most homosexuality is not DNA polymorphism(s), but epi-marks that evolved to canalize sexual dimorphic development that sometimes carryover across generations and contribute to gonad-trait discordances in opposite-sex descendants.
2. This 2014 study also shows a large role for epigenetics in both women and men. Check out pages 172-177 in this reading: https://books.google.com/books?hl=en&lr ... cs&f=false

3. This 2015 study shows a genetic (not epigenetic) link for male homosexuality, but does not find such a link for females: http://cshperspectives.cshlp.org/conten ... 7657.short

4. This 2011 research finds that atypical prenatal hormones exposure is linked to homosexuality in both men and women: http://www.sciencedirect.com/science/ar ... 2211000240
[color=red]Hines 2011[/color] wrote:Prenatal exposure to androgenic hormones influences human sexual orientation. â–º Androgen dose predicts the likelihood of non-heterosexual orientation. â–º Normal variability in testosterone prenatally predicts masculinity in childhood. â–º Sexual orientation is predicted by masculinity/femininity of childhood behavior. â–º Prenatal stress does not demasculinize boys, but may masculinize girls slightly.
5. Finally, this 2012 study also shows the same link between prenatal androgen exposure and homosexuality in both women and men: http://link.springer.com/article/10.100 ... 9-z#page-1
[color=blue]Hiraishi et al. 2012[/color] wrote:Female monozygotic [identical] twin pairs discordant in sexual orientation showed significant within-pair differences in left hand 2D:4D, where non-heterosexual twins had lower (more masculinized) 2D:4D. In addition, we found that non-heterosexual male MZ twins had larger (more feminized) 2D:4D than their heterosexual co-twins. These results suggest the existence of non-shared environmental influences that affect both 2D:4D and sexual orientation.
In sum, a brief survey of the recent research shows that homosexuality is likely caused by a combination of genetic, epigenetic, and hormonal factors, and that these are all what would be considered innate.
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Post #8

Post by OpenYourEyes »

Thanks Haven for inviting me to debate this issue with you and thanks in advance to all readers. I’m actually surprised that this will be the first head-to-head debate on this forum site that deals with homosexuality given the amount of debate and passions surrounding this issue. I hope that this will be productive and engaging both to us and the readers!

My position
I will be arguing that it is not scientifically justified to claim that homosexuality is innate, and I will do so by refuting Haven’s arguments. For the record, I don't claim that there is no scientific evidence for homosexuality being innate, but rather my view is that the evidence is not sufficient to draw any conclusions that we can settle on in terms of causation. Therefore, I take the Agnostic position on this issue.
Haven wrote: 1. Homosexuality is defined as the exclusive attraction to members of the same gender. It has nothing to do with sexual activity, only attraction.
Agreed.
Haven wrote: 2. Innate is defined as determined by genetics, hormones, and/or brain structure before birth or during early development. It doesn't necessarily mean that the trait (in this case, homosexuality) is present at birth, but that it will develop at some point during the life course due to the aforementioned factors. If something is innate, it is not chosen or determined by environmental factors.
I agree with everything you’ve said here except for the parts that I changed to red bold font. The reason I don’t accept those parts is because your claims involve homosexuality being determined BEFORE birth and based on biological factors, and elsewhere you’ve also defined “innate� to refer to pre-birth.
Haven wrote: Before getting to the actual evidence, I just wanted to clear up one thing first:

The goal of this debate is to discover the most likely explanation, not to gain absolute certainty. As with all things in science, nothing can be known with absolute certainty, and so asking for such proof is an unreasonable request. My aim here is to advance the position that homosexuality is as likely to be innate as, for example, influenza is likely to be caused by a virus. This is a very high level of certitude, of course, but it's not absolute.
I agree with you here, especially the part of your statement that I changed to red bold font. We know the cause of the flu illness, and the debate question should be answered to the same level of certainty. While we may not be able to attain absolute certainty, but we can at least obtain scientific justification by ensuring that studies yield valid results to justify a conclusion and that the study is consistently and independently replicated to further ensure validity. This is important because it’s possible for scientific studies to be faulty or invalid because of various non-scientific factors, including dishonesty on the part of researchers.

My rebuttal
I will mainly focus on the prenatal hormone exposure theory for homosexuality since that is what much of Haven's argument centers on. I'll start out by explaining what the theory is so that people understand it including my points about it, and then I'll go on to address Haven's specific arguments. If you already understand the prenatal hormone exposure theory for homosexuality and how it's tested, then you can skip the next 3 Q/A below, but still read the 4th or last Q/A.

So what is the prenatal hormonal theory for homosexuality? Here's my sum up:
This theory uses the fact that a fetus is exposed to prenatal hormones, primarily androgen, as it develops. Androgens (e.g. testerone) are hormones that stimulate and control sexual differentiation (development of typical female or male characteristics) during fetal development and beyond. Exposure to a high concentration of androgen during a critical phase of development would lead to male-typical traits whereas low embryonic exposure to androgens would lead to a female-typical triats or characteristics. Now some of the researchers who believe this causes homosexuality do so because they view sexual orientation as a sexually differentiated trait, as well. This means that exposure to a high concentration of testosterone leads to a male-typical orientation (attraction to women) as is normal for most men; and a lower exposure to androgen leads to female-typical orientation (attraction to men) as is normal for most females. Gay males would be underexposed to androgen which leads to them having female-typical orientation (attraction to males) and the same logic applies to lesbians when it comes to overexposure of androgens [1].

How is this theory tested?
Researchers resort to testing this theory through indirect means because it is considered unethical to try to manipulate the process of androgen exposure for experimental purposes [2]. What's tested are sexually differentiated traits that tend to correlate with androgen exposure, like the ratio of the 2nd digit (index finger or pointer finger) to the 4th digit (ring finger) or 2D:4D in men and women. One article further explains, " Much of this research has focused on the ratio of the length of the second digit of the hand to the length of the fourth digit, a ratio that has been termed 2D:4D. This ratio is larger in women than in men and the sex difference is thought to develop under the control of androgenic hormones prenatally." [3] Therefore, high androgen exposure is associated with low 2D:4D ratio as seen in males, and low androgen exposure correlates with a high (higher than males) 2D:4D ratio. Gay males would have a 2D:4D ratio that's similar to heterosexual females and lesbians would have a ratio similar to heterosexual males.

What's the role of epigenetics that Haven references?
The epigenetics perspective is comes into play here in that epi-marks (temporary switches on a gene) that are supposed to protect the fetus from overexposure of androgen (this is supposed to be in females) and underexposure (in males) is passed down to the wrong sex. That is, males inherit epi-marks that do not minimize underexposure leaving them at risk for underexposure of androgens and conversely females inherit an epi-mark that does not protect them from overexposure [4].

So is the prenatal hormone theory along with an epigenetic twist enough to account for homosexuality?
No. I'll get to specifics as I address each of Haven's sources later on. The reason why I don’t accept homosexuality is innate is because there is no established biological mechanism that can fully account for homosexuality, pre-birth or otherwise. This also means that the external environment can not be fully ruled out eventhough some factors have been tested and have been shown to have no effect on homosexuality. Either way, in general what you’ll usually find is that studies that claim to find some biological cause fall short in that the propose cause doesn’t apply to all subjects, women and men, alike. Also, replications of these proposed causes tend to not be successful which means that subsequent studies tend to not support the original or previous studies. You can not draw a reasonable conclusion from this and it certainly falls short of being a scientific justification which is why even the American Psychological Association considers the causation matter as being unsolved [5].

Now on to the specifics of Haven’s referenced studies…
Haven wrote: Now, on to the evidence. For this, I will present five recent studies, each of which present strong evidence that homosexuality is innate in both women and men:

1. This 2012 study links homosexuality (in both lesbians and gay men) to epigenetic factors: http://www.jstor.org/stable/10.1086/668167 . Specifically, it states:
[color=green]Rice, Friberg, & Gavrilets 2012[/color] wrote:We show that an unappreciated feature of this process is reduced androgen sensitivity in XX fetuses and enhanced sensitivity in XY fetuses, and that this difference is most feasibly caused by numerous sex-specific epigenetic modifications (“epi-marks�) originating in embryonic stem cells. These epi-marks buffer XX fetuses from masculinization due to excess fetal androgen exposure and similarly buffer XY fetuses from androgen underexposure. Extant data indicates that individual epi-marks influence some but not other sexually dimorphic traits, vary in strength across individuals, and are produced during ontogeny and erased between generations. Those that escape erasure will steer development of the sexual phenotypes they influence in a gonad-discordant direction in opposite sex offspring, mosaically feminizing XY offspring and masculinizing XX offspring. Such sex-specific epi-marks are sexually antagonistic (SA-epi-marks) because they canalize sexual development in the parent that produced them, but contribute to gonad-trait discordances in opposite-sex offspring when unerased. In this model, homosexuality occurs when stronger-than-average SA-epi-marks (influencing sexual preference) from an opposite-sex parent escape erasure and are then paired with a weaker-than-average de novo sex-specific epi-marks produced in opposite-sex offspring. Our model predicts that homosexuality is part of a wider phenomenon in which recently evolved androgen-influenced traits commonly display gonad-trait discordances at substantial frequency, and that the molecular feature underlying most homosexuality is not DNA polymorphism(s), but epi-marks that evolved to canalize sexual dimorphic development that sometimes carryover across generations and contribute to gonad-trait discordances in opposite-sex descendants.
First off, Haven’s first referenced source that he calls a study is not a study but instead is a proposed theoretical model or hypothesis. The researchers allude to this in the Discussion and Predictions section of the article and in Haven's 2nd referenced study on pg. 174, 2nd paragraph going into pg. 175. There’s no mention of any subjects, results, and experiments that specifically examine the researchers proposed model so it has not been scientifically tested.

Secondly, the researchers in Haven’s first study base their model, in part, on the prenatal hormonal theory for homosexuality. As I explained earlier, the theory is tested by examining the 2D:4D digit ratio and heterosexual males and lesbians are supposed to have a lower ratio than women and gay males but replications have not been consistent. Here are studies that not only conflict with other studies but also with the prenatal androgen theory:
Prenatal Influences on Sexual Orientation: Digit Ratio (2D:4D) and Number of Older Siblings
As in many previous studies, heterosexual men had lower 2D:4D than non-heterosexual men, which supports the notion that nonheterosexual men experience higher androgen levels in utero than population norms. Contrary to previous reports, non-heterosexual women had higher 2D:4D than heterosexual women.
This is a conflict because non-heterosexual females are supposed to have a low 2D:4D ratio similar to heterosexual males.

Another study...
Differences in Finger Length Ratios Between Self-Identified “Butch� and “Femme� Lesbians
From Abstract:
We conclude that increased early androgen exposure plays a role in only some cases of female homosexuality, and that the sexual orientation of “femme� lesbians is unlikely to have been influenced by early androgens.

From Discussion section:
We have so far detected no difference between heterosexual and homosexual men in 2D:4D, suggesting that early androgens do not differ between the two groups and may not play a role in the development of male sexual orientation.
This study conflicts with my first referenced study in that gay males had the same 2D:4D finger ratio as hetero males instead of having different ratios. Also, "femme" lesbian females had similar 2D:4D ratios to heterosexual women. Even if we threw in the epigenetic model from your first referenced study and said that these women did not inherit the wrong (sexually discordant) epimarks which led them not being exposed as much to androgen, its still a conflict because these "femmes" are still gay. This takes away from the explanatory power of the epigenetics factor when it's not even needed for homosexuality to exist.

I can present you with more conflicting studies, as well, if you'd like. I believe what I posted is suffice to show that the epigenetics model is based on an inconsistent foundation which takes away from its validity, even on a purely theoretical scale.
Haven wrote:2. This 2014 study also shows a large role for epigenetics in both women and men. Check out pages 172-177 in this reading: https://books.google.com/books?hl=en&lr ... cs&f=false
Your second source here is not a study nor does it provide experimental data/results on the epigenetics mechanism from your first souce. Pg. 175 of your source actually gives some critiques of the epigenetics model, and even considers that it does not apply in male homosexuality. On the same page, the author considers thst causal mechanisms for homosexuality may not even be the same for men and women since women's sexuality is different on average. Women's sexuality is much more fluid. Also, environmental factors are not ruled out per your source, pg. 172, last paragraph going into pg. 173

So again, just as in your first source, there's a lack of empirical testing and failed replications, therefore no scientific justification as of yet.
Haven wrote:3. This 2015 study shows a genetic (not epigenetic) link for male homosexuality, but does not find such a link for females: http://cshperspectives.cshlp.org/conten ... 7657.short
This is not a study but rather a theory that tries to explain the origins and persistence of homosexuality in human populations. It's an unrelated mechanism to your previous two studies so i dont see it as being part of any replication unless it involves testing prenatal androgen perspective, epigenetics, etc, which it does not. So this doesnt help your case, especially in terms of providing scientific justification.

This is why before the debate, I asked for a distinct mechanism that could account for homosexuality to prevent ANY or all biological mechanisms that you can think of being thrown at me.
Haven wrote:4. This 2011 research finds that atypical prenatal hormones exposure is linked to homosexuality in both men and women: http://www.sciencedirect.com/science/ar ... 2211000240
[color=red]Hines 2011[/color] wrote:Prenatal exposure to androgenic hormones influences human sexual orientation. â–º Androgen dose predicts the likelihood of non-heterosexual orientation. â–º Normal variability in testosterone prenatally predicts masculinity in childhood. â–º Sexual orientation is predicted by masculinity/femininity of childhood behavior. â–º Prenatal stress does not demasculinize boys, but may masculinize girls slightly.
My point and references involving inconsistent studies apply to this source of yours, as well. Prenatal androgen exposure does not fully account for homosexuality.
Haven wrote:
5. Finally, this 2012 study also shows the same link between prenatal androgen exposure and homosexuality in both women and men: http://link.springer.com/article/10.100 ... 9-z#page-1
[color=blue]Hiraishi et al. 2012[/color] wrote:Female monozygotic [identical] twin pairs discordant in sexual orientation showed significant within-pair differences in left hand 2D:4D, where non-heterosexual twins [female non-hetero twins] had lower (more masculinized) 2D:4D. In addition, we found that non-heterosexual male MZ twins had larger (more feminized) 2D:4D than their heterosexual co-twins. These results suggest the existence of non-shared environmental influences that affect both 2D:4D and sexual orientation.
Refer to my response for your #4 source. Here's a study that conflicts with the part I put in bold font:

From Are 2D:4D Finger-Length Ratios Related to Sexual Orientation? Yes for Men, No for Women - Abstract..
Heterosexual and lesbian women showed no significant differences in 2D:4D ratios, after ethnicity was taken into account
It appears Haven, that you have not provided any scientific justification for your side of the debate. You can't draw any real certain conclusions based off of inconsistent results, and besides that, you really did not provide any real studies, except for your very last source.

References
1. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3138231/ - A Hormonal Theory of Homosexuality section 3rd and 4th paragraph
2. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3138231/ - A Hormonal Theory of Homosexuality section 1st paragraph
3. Prenatal endocrine influences on sexual orientation and on sexually differentiated childhood behavior - Bio-assay of prenatal androgen exposure and sexual orientation: The 2D:4D ratio section, 1st paragraph
4. Epigenetic Shaping of Sociosexual Interactions: From Plants to Humans – Pg. 172, 1st paragraph and pg. 174, 1st paragraph.
5. American Psychological Association - click on the section called, What causes sexual orientation?

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Post #9

Post by OpenYourEyes »

Hi Haven. You can make your post today as scheduled but i am temporarily suspending my participation in this thread until some issues are addressed between the moderator and i. Ideally, it will be resolved today.

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Post #10

Post by OpenYourEyes »

OpenYourEyes wrote: Hi Haven. You can make your post today as scheduled but i am temporarily suspending my participation in this thread until some issues are addressed between the moderator and i. Ideally, it will be resolved today.
Looks like nothing will be resolved anytime soon. I am throwing in the towel because i no longer feel good for a serious debate on the site. You win. Good luck with your last post.

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