SamTheSkeptic

SamTheSkeptic:

 

I will try again. Please explain the following. I will try to make this as simple as possible:

 

Both genes and behaviors are measurable, quantifiable, and measurements are repeatable.

I don't agree with you that human behavior is quantifiable, scientifically measurable, or repeatable. I am sure that I'm not the only person with this view. . .Sure, one can observe human behavior, chart it, graph it, compile statistics on it, but that doesn't mean that the phenomenon is actually explained or understood. As I said before, there exists no objective scientific scale for "love" or "risk taker." And if human behavior tests were truly "repeatable," then the same exact results would appear every time without any exceptions. This clearly is not the case, as human behavior is highly unpredictable.

They are both legitimate topics of scientific investigation.

They are legitimate topics of investigation; just in my opinion, not scientific investigation. I never meant to imply that there lies no value in attempting to understand and explain human behavior, I only contend that it presents an inherent impossible feat for science. Science will never be able to "dis-prove" your claims just as science can never "dis-prove" that God exists.

If one gets a repeatable correlation between a specific genetic background and a behavioral measure, then this is a legitimate scientific result.

This just simply isn't true. Under this logic, because African-Americans statistically show to be more violent and commit more crime (behavioral traits) than Caucasians, it would be 'scientifically legitimate' to attribute this behavior to their genetic background? Of course not. A correlation is just a correlation, nothing more. Once you are able to explain the phenomenon with a cohesive and testable theory, then you will have legitimate science.

You might argue that the name of the behavioral construct isn't accurate, but you cannot deny the principle that genes have been shown to relate to complex behavior.

I don't argue that the name of the behavioral construct isn't accurate, but that it is merely a construction of our minds in an attempt to understand the unexplainable phenomenon of our thoughts and emotions. This concept is a subjective one, not concretely defined, one that changes a bit from person to person. . .therefore, it is not a scientific principle.

Also I do deny that genes have been shown to relate to complex behavior. Nothing at all has been "shown" here. . . It takes more than correlations to show (prove) something in science.

The logic of what you say is very difficult to follow. In my statement my use of the word "partially" is clear and refers to the behavior genetics truism that Phenotype = genotype X environment (P = G X E) and it unequivocally does not follow, as you say, that identical twins should be identical when reared apart (or together, for that matter). Behavior genetics research specifically tries to partition effects into environment and genetic components. Your "identical" assertion is illogical and a strawman argument.

First off, not all scientists agree that behavior should be included within the definition of "phenotype," but this is another issue. Even then, my example is far from illogical. In your 'behavior genetics truism' (P=G X E), imagine two individuals (twins) with the exact same genes and environment (G and E). Then, the phenotype, or P, (which includes behavior according to your definition) should be exactly the same. But in reality, they are not. There are always at least slight differences, which because we already know that their Genes are exactly the same, must be attributed to environment.

You have refused to answer the following. You have made the claim that complex human behaviors, such as personality, are totally due to experience with no genetic component....This suggests the simple and straightforward question- How does your statement logically exclude genetics but not environment as a scientifically verifiable causative factor? In other words, if there is no way to define it, there is also no way to make a choice. Please respond to this.

 

SM

I have already answered this many times. My position logically excludes genetics because I am aware that human emotion/thoughts/behaviors are outside of the realm of science. Would I spend my time "scientifically researching" the existence of God? No, because I understand that God, like the ideas of Love or Hate or Intelligence, are in essence only constructs of the human mind and they cannot be objectively measured or quantified.

I also understand that attempting to do so may be interesting and fun, but ultimately will not yield results which lead to their scientific explanation.

The last part of your statement is a fallacy, as I have also specifically pointed out before. I have heard this argument used a million times, I specifically remember Bill O'Reily trying to use it in his interview with Richard Dawkins. I will use God as an example again. . .my disbelief in God is not a "choice" in itself. Rather, those who believe in God are the ones actually making a choice. They are taking the leap of faith - without conclusive supporting evidence - not me. When they try to turn around and say that "atheism" is itself a belief, this is simply illogical. Yet this is exactly what you are doing here. . .

Since when do legal implications have anything to do with scientific accuracy?

Ever heard of Forensics? Scientific Expert testimonies? CSI !?!?

Scientific accuracy couldn't be any more important when it comes to human lives and/or freedom.

SamTheSkeptic, I have to concur that you are making straw man arguments, and using them to engage in appeal to ridicule. Logical fallacies are not valid arguments and are not permitted.

I'm sorry, but my argument is not fallacious at all. All of my points are valid and have been based in logic. Nowhere have I constructed a straw man. If you'd like to be specific, I certainly can explain further on anything I've said to clarify. . .

And my point is certainly not to ridicule or anger anyone. . .this is a forum for scientific discussions - and although this one may seem a bit heated, everyone here is playing by the rules and I'm sure someone can take something useful away from this thread. My position is very simple and consistent. I refuse to accept speculations as scientific theories (hence my screen name).

"Nature vs nurture" studies exist (e.g. with twins) and broad dismissals of them is unfounded.

I never said that I "broadly dismiss" these studies; but I certainly do question the validity and significance of their results and implications. This is the very nature of science - until something is explained definitely and absolutely, we must consider with equal importance all other possibilities. How could you consider this to be "unfounded?"

SMF, let me say firstly that I have no personal feelings against you. . .believe it or not I have enjoyed having this exchange with you and I appreciate your replies. Hopefully the OP and others have pulled something from this as well.

You are at least consistent. You refuse to bring any science to the conversation.

I am not refusing to bring science into the situation; rather, science is refusing to explain your claims. In the same way that science can't be applied to uniquely human concepts such as deities, neither can it be used to explain human emotions. This is the field of psychology.

Your way of looking at science has little relationship with reality.

Actually, "my way of looking at science" is completely necessary for achieving the best available understanding of reality. There is no debate about the theory of gravity for example, because the evidence is overwhelming and physically available for anyone who inquires to confirm it. Indeed, if a single person were to ever conduct a test or produce a situation in which gravity "broke down" or didn't hold true, then the theory would be falsified and no longer considered to be the best understanding of reality.

But your position lacks this kind of testability. There is no definite theory which can be used to fully explain and accurately predict future outcomes. It is only a speculation; and there are many exceptions to your speculation, even in the very studies (twin studies) you have cited. For example, according to your claim that "genes partially influence human behavior," it should prove true that "two identical twins should, theoretically, be exactly the same in all respects, even if reared apart. But a number of studies show that they are never exactly alike, even though they are remarkably similar in most respects. " If your claim was truly a scientific theory (and not just a speculation), then this single finding alone would be sufficient to falsify it.

You are trashing a lively and legitimate area of research with your uninformed opinion. In short, you are trolling.

I never have "trashed" anyone's attempt to document and/or understand reality, as long as it has valid scientific relevance and significance. Part of my reasoning for being so critical of the "nature" side of the debate is because of the legal implications that it may have. If eventually your view (which is currently the most popular) becomes generally accepted, then how many people will be able to get off the hook for murder because they were "genetically prone to violent behavior" ? How many sex offenders will have their sentences reduced because they had the "sex offender gene" ? Also, disagreeing with you doesn't equate to trolling.

SamTheSkeptic:

 

 

The obvious falsifiable theory that is being tested is- Heritability can explain some percentage of the variance of some specific complex human behaviors. This theory has been verified repeatedly and is being refined.

No, this is a speculation, not a falsifiable theory. How can it be falsifiable if you can't even give specific measurements? Heritability can explain "some" percentage of "some" human behaviors? Exactly how much? What specific behavior(s)? Could you possibly be any more vague? Do you think that such a sloppy "Theory" could provide us with any reliable information? The answer is no.

In order for this to be falsifiable, you would need to define an exact percentage and an exact behavior first. This would be your hypothesis. Then you would have to be able to reproduce the results over and over again to confirm this hypothesis. If you came out with a different result even once, you know that the theory couldn't be the best way to explain the phenomenon.

Really what you mean to say is that extensive observational studies (which fall into the realm of psychology and not science) have been done which show correlations between genes and behavior. But this is far from a scientific theory.

If science progressed in the manner you think it should then we would not have evolutionary theory, modern physics, modern neuroscience, and who knows what else because the researchers didn't have a complete theory at the beginning.

No, you're mistaking a theory with a hypothesis...as I explained above. In order to come up with a scientific theory, you need a specific hypothesis first that can be precisely defined. The sloppy evidential standards you proposed in your 'theory' above are quite simply insufficient to produce quality results.

Descriptive statistics of human behavior is quite valuable both in and of itself and because they can be related to some other variable, such as genetics. This is science. Behavior geneticists have demonstrated a relationship and, along with neuroscientists, are looking for biological mechanisms. Astrologers have not demonstrated a relationship between astrological sign and behavior and are not looking for a mechanism, and scientists can't even think of a research direction for this. This is another straw man argument.

Descriptive statistics are valuable to psychologists, not so much for scientists. And no, "behavior geneticists" and neuroscience have not scientifically defined or explained the relationship. . they simply have said "our observations seem to suggest a link." And in many cases, they even use those exact words!

In this statement, you have presented a fallacious argument. It is perfectly valid for me to ask you to support any assertion you make. It sounds to me that you don't think science regarding the nature nurture question is valid at all. Perhaps you should check out astrology for an answer. No? Then answer this- Why do you think that if "personality and character cannot be explained scientifically," that experience explanations (nurture) are valid, but genetic explanations (nature) are not? No more hand waving please.

Incorrect. Sure it would be valid for you to ask me to support my assertion. . but I haven't made any assertions (as I've explained earlier numerous times). My skepticism of your claim is not in itself an assertion or a claim!!! THIS is the fallacious argument. No hand waving necessary, it really is as simple as that.

I suggest that you take your own advice for the following- It is scientifically valid to study how variability in the genetics of any organism affects variability in resulting body structure, function, and behavior. If you don't believe this, please explain. No more hand waving please.

Body structure yes. Behavior, no. I've already explained plenty. . but in a nutshell, you are attempting to sell (poorly disguised) psychology as a science, and I'm not buying.

I think this thread should be moved to the Speculations section. SM

Great idea, considering that behavior being determined by genes is really a speculation.

SamTheSkeptic. You say-

 

 

 

This statement is nonsensical. Personality and character constructs are based on the output of our complex biological computers (brains). There is no representation of "risk taker" in the brain, but it is a demonstrable component of behavior.

My statement makes perfect sense, you are just failing to understand it. As I said before, show me a falsifiable theory that fully explains how genetics exactly predetermine one's personality, and I will accept your claims. But the truth is that you can't. . .none of the studies you have provided (and there are indeed none out there at all) provide conclusive evidence for this.

This behavior is well defined in culture and by scientists who wish to study it (in the studies I have cited) so I challenge you to provide scientific evidence, no more opinions, of any representation of this concept "inside our minds." Don't imply that this is obvious because this is just your opinion. Both genetics and experience affect the processor and, thereby, the output, and this has been reliably measured by researchers.

Again, you fail to understand that observing human behavior (including representing the observations with bell curves, graphs, constructed scales, etc.) does not make it science. You need to have a falsifiable theory, I'll say it time and time again. Here's a particular example that I enjoy from an article written by Paul Lutus:

" Let's say I am an astrologer, and I want to carry out a research project — I want to statistically break down the U.S. population by astrological sign. That way, I can order supplies intelligently and focus my efforts appropriately, with an evidence-based idea of who my clients will be. So I consult a statistical database of U.S. births by date, process the data, and break it down by the astrological "signs" (this result is for U.S. births in 2003):

Okay. I have created a scientifically valid statistical result in astrology, and the study turns out to have practical value in the daily activities of astrologers. Does this scientifically valid result make astrology itself scientific? No, of course not. Why? Because, regardless of its practical significance, my research doesn't address or potentially falsify the core theories of astrology."

Please drive this principle into you head. These studies you are citing do not make your argument scientific!

This bit demonstrates your lack of understanding of how science works. Most phenomena, and especially biological ones, can be represented by the ubiquitous normal (bell) curve. Scientists who study behavior can define a trait, such as risk taker, operationally for research. This typically might be behavior tested to be two standard deviations from the mean. This operational definition is more than adequate for performing a study that relates heritability to behavior. Defining risk is actually very easy. It is based on how often the behavior results in a bad outcome. If you think that there is disagreement about this prove it with science, not opinion.

Funny that even after I have explained (and pointed out that it is often overlooked) the fact that you are the one who is making the claim and you are the one who needs evidence, you still overlook it. You asking me for evidence is like asking an atheist for proof that god doesn't exist...it is a fallacious argument.

You make a claim, I am skeptical of that claim - but you can't turn around and then label my disbelief as being a belief in itself! I hope you see that you're falling into this simple fallacy.

SamTheSkeptic:

 

I am very surprised at your statements regarding "scientific measurement for character or personality" being impossible.

Well, I'm not surprised that you're surprised. Most people don't realize this, but it really is at the foundation of the entire debate. At the same time, you shouldn't be surprised that it is impossible to scientifically measure a concept that only exists inside our minds. . .

For example, it is common to say that somebody is excitable, or a risk taker, or is trusting, or tends to be melancholy and the meaning is clear to others. The fact that we all are able to communicate these complex character traits to one another indicates that they are real and verifiable behaviors. The point is that they are behaviors and are easily measured.

Let's delve a bit deeper into your example. Sure, we have all heard the term "risk taker." I don't disagree that we all know the general concept of what it means to be a 'risk taker' - obviously, it is a term given to those who take risks. But how much risk does a person have to take in order to be considered a "risk taker" ? I mean, we all take risks in our life at some point or another. ..indeed, from driving in cars to flying in airplanes to even taking a shower! This then begs the question, "what constitutes a risk?" And then, if this question were to somehow be universally answered and agreed upon, how many risks would one have to take in order to be deemed a "risk taker? The problem is coming up with a scale that exists objectively to measure the risk; that's the impossible part. There are pH tests to measure acidity and blood tests to measure HIV, but no such tests to measure "risk."

And many 'behavioral scientists' do attempt to create standardized scales for such concepts. Intelligence (another concept that exists only in our minds and not objectively) is an example, along with the IQ tests intended to assess it. I'm sure many would even consider IQ tests to be scientific, but in reality they are not. I won't get into the origins of the test itself, but the standards used on the test are certainly arbitrary. . . And that isn't to say anything about the uselessness of the results. A person's IQ score many times seems to be in stark contrast with how others perceive their abilities and accomplishments. If it were a scientific measurement, this would never happen.

You say that the meaning of these concepts are "clear to others," but I think you might be surprised at the amount of disagreement you may come to with others pertaining them. One's trust might be viewed by another as being "weak," and what you may consider to be melancholy may not feel like melancholy at all to someone else. True science doesn't change at all from person to person. . .something either IS or it ISN'T, and there are ways to test/disprove it.

Some of the best evidence for the heritability of complex behavioral traits can be found in twin studies. There are two big ones, the Minnesota twin study- http://mctfr.psych.umn.edu/ where you can find links to research from their database and the Swedish twin study for which I couldn't find a website, but you can see an enormous amount of research for both by putting the twin study name in the search field in Google Scholar. The reason this is such good research is that it is relatively easy to statistically measure heritability from behavioral comparisons of identical twins reared together and apart and non-identical twins reared together and apart. There is a very large research literature on this topic.

 

Here are some links to good research. I have tried to provide full text links where possible.

 

T.J. Bouchard twin study- http://www.sciencema...78/223.abstract, full text- http://www.psych.umn...uchard_1990.pdf

 

Behavior study using Swedish twin data, the full text link is on this page- http://www.pnas.org/...5/10/3721.short

 

Heritability of personality dimensions- http://www.psych.umn...t%20al_1996.pdf

 

Here is one on homosexuality- http://faculty.benni...esex%202010.pdf

 

You might also be interested in Robert Plomin's work- http://www.sciencema...5166/1733.short

 

I have seen these studies before, and they all lack the same scientific validity because they never actually explain the causes they study! For example, taken from the

Minnesota twin study website, "While we still use and have much to learn from twin and adoption study techniques, the successful mapping of the human genome now provides scientists with an exciting opportunity to build on these important findings. Your DNA sample, when related to the extensive behavioral information you have also provided, will lead to a better understanding of how and why genetic factors appear to shape human behavior. "

I've put the important parts in bold, lol. They still "have much to learn from study techniques," and the "exciting opportunity to build.. . .Genetic factors appear to shape human behavior." What this really means is that they have no conclusive explanation or proof for genetics playing any role whatsoever in human personality. They might have lots of correlations and observations, but no cohesive theory that actually explains the phenomenon. Do you think NASA could send people to space if it "appeared" that they would be able to re-enter the earth's atmosphere without incinerating? Could an engineer design a bridge that "appeared" to be safe? Of course not. . rigid and strict precision is required for accomplishing such great tasks. . and real science provides this.

As for my thought experiment, your answer is very confusing. You seem to be saying that personality and character are completely determined by experience, as opposed to inheritance, but that you couldn't tell. If you can't tell the difference then you also can't assign these traits to either cause.

 

SM

Yes, I am saying that personality and character are completely determined by experience and environment...they are merely concepts which although can be generally agreed upon in terms of their definition, have different meanings for different people. Science has the same meaning for everyone. I can't drive this point home enough.

SamTheSkeptic:

 

You appear to be a relatively strong adherent of the Tabula Rasa (http://en.wikipedia....iki/Tabula_rasa) side of the nature/nurture question.

I am indeed. I think it is important to point out though, that although the 'nature vs. nurture' debate is largely considered to be a philosophical one, real science does play an important role as well. Just how does science play into it? Well, science prevents the proponents of the "nature" side from ever validating their claims. In essence, the whole debate revolves around their claim - that human behavior is (at least partially) genetically predetermined - and the lack of scientific evidence to support that claim. The proponents of the "nurture" side don't need scientific evidence to validate their position because they are aware that personality and character cannot be explained scientifically!

If you don't think that ones genetic background has any effect on the development of complex personality and other character traits, I presume you believe that, in a thought experiment, a group of children from diverse genetic backgrounds that were all raised in exactly the same environment would become a group of adults that would all be, essentially, the exact same person. Is this true?

No. The problem with trying to apply this hypothetical 'thought experiment' (which I have heard presented before) is that there is no objective scientific measurement for character or personality (because they are non-scientific concepts). So, even if this this experiment were to be properly conducted on a sufficient enough sample to yield meaningful findings, in the end there would be no reliable test to determine whether or not the individuals in the study actually turned out "the same." Who would decide how much "alike" any two given individuals are? What would that decision be based on? Surely, it would be a self-reporting problem...and in the realm of psychology, not science.

Also, what is the deal with your citing two studies that disagree with you contentions.?

 

SM

I figured I'd give a few examples from each viewpoint, since the poster implied that they were writing an essay on both sides of the debate. Maybe I should have pointed that out to avoid confusion. With that being said, I did pick out the dancing gene study because I find it to be particularly amusing. . .

Does nature or nurture (hereditary or environment) influence the development of one's identity more?

When you use the word "identity," I assume that you are referring to an individual's personality or character, rather than their physical appearance.

The study of personalities and character is Psychology, which really isn't a science... it is an attempt to understand and explain the human mind (which can't be accurately done as of present day). No one can scientifically explain human behavior - why we act the way we do, feel the emotions we feel, and take on the personalities which define us - despite what you might have read in the latest pop-science newspaper article or best selling psychology book. There is no chemical test, for example, that can be ran to detect certain types of personalities. You can't take a blood test and find out if you are positive for homosexuality. As ridiculous as this may seem, this is exactly what proponents of the "nature AND nurture" delusion are implying. If nature (genes) were at all involved in the formation of "character" and "personality," then it would be theoretically possible to have such tests to detect them. They simply don't exist, because personalities and character are not genetically predetermined.

Think of it this way: genes provide you with your physical brain (the organ itself) and its components... so in this sense, I suppose that genes are 'partially responsible for behavior', which is the phrase you so often hear parroted today. But really, what you do with your brain after it reaches its physical genetically predetermined growth limit, is not determined at all by genes. After this point, you begin crafting your own personality and emotional scale based on the people and things you see and hear around you. This is 0% genetics, and 100% environment.

Scientifically, what are the arguments presently for each stance?

It isn't evidence, but a lack thereof that you should be concerned with when it comes to the position that personality is genetic. There is already plenty of scientific evidence out there regarding hereditary physical traits. . .certainly tests can be done to determine them and it really doesn't take a scientist to see striking similarities between some children and their parents (I look just like my father for example). There is no question that I look the way I do because it was genetically predetermined.

But there is no such undeniable conclusive evidence regarding the responsibility of genes in the development of one's character. If there were, it would be big news!

What you do see are lots of speculative and misleading articles and books, published each year, bombarding us with a plethora of new opinions and hunches but never a conclusive and testable theory.

With that being said, here are some sources I can offer up for your research paper. I hope you find some useful stuff, good luck.

AVPR1a and SLC6A4 Gene Polymorphisms Are Associated with Creative Dance Performance

http://www.plosgenet...al.pgen.0010042

Bad News for the Genetics of Personality

http://neurocritic.b...ersonality.html

The Personality Paradox

http://www.wired.com...nality-paradox/

The heritability of personality is not always 50%: gene-environment interactions and correlations between personality and parenting.

http://www.ncbi.nlm....pubmed/19012656

Quite the contrary. You are the one who has absolutely no evidence, yet you promote the "possibility" of genetic components in homosexuality. This is why I brought up the spaghetti monster. . .I could just as easily promote the "possibility" that he exists, despite any falsifiable evidence. Just because you aren't able to understand the analogy doesn't mean it is an invalid one.

And please note that it isn't I who needs proof. . I'm not making the claim here. You need proof because you are making the claim that homosexuality has a genetic component.

Don't misconstrue my skepticism as a claim!

You state plainly that homosexuality is an unexplainable peheomena which can be explained entirely by environmental factors ( it has everything to do with environmental conditions and influences). That is a contradiction if ever I seen one.

Homosexuality certainly does have everything to do with environmental conditions and influences (just like any other human behavior). . but no one knows exactly which conditions/influences are required to produce it. There are plenty of pet theories and hunches, but no sound evidence. Therefore, it is still an 'unexplainable phenomenon' although it can be fully attributed to environmental factors and not genes. No contradiction at all. . nice try though.

Going back to the flying Spaghetti Monster stuff, the simple fact you used that term (in this barely relevant context) made me cringe. The fact you seemed to believe it appropriate made me feel a little bad for laughing. If I had said that ''God creates homosexuals no further info requred'' then yes this comment would have been fine, even a little funny. I didn't say that though. If I had even said that DNA definitely causes homosexuality you might have had some sembelance of a case. I did not say that though. I simply said that it was plausible that DNA (the source of a significant portion of our behaviour) could plausibly be a factor in incidence of homosexuality. The fact that the mechanism is likely to be beyond our understanding does not mean that we should automatically decide that it is something else. That is about as unscientific as it is possible to be.

I already addressed this in my first bit of this reply. The spaghetti monster analogy is perfectly valid and applicable to this situation, but you are seemingly ill-equipped to comprehend how it applies. Your approach is the same as someone who believes in god, but whose only evidence is "you can't prove he doesn't exist, so therefore the possibility is still there!" In science, theories reign supreme my friend, and possibilities come a dime a dozen!

Again I really do hate to get angry/be rude, but your arguments make no sense. Genetics cannot play a factor in sexuality becuase of the repercussions that might have on people who steal lol? You are starting with a conclusion and looking back and hoping to see the evidence that will support what you think is right. There is no grater ''crime'' in science (lol) but I'll try and respond coherently anyway pal.

My arguments make plenty of sense. . however a bit more thinking seems to be required on your part. You quite simply have misconstrued and butchered just about everything I have said and somehow twisted it into your own distorted perceptions lol. Yes, I am saying that genetics can't have anything to do with homosexuality (or any other human behavior other than perhaps some instinctual ones which all humans share). Homosexuality is a behavior, no? It is something that someone can choose to become half-way through their life if they so desire. Many people do in fact turn gay, or turn straight at different points in their lives. If this was genetic, or had any genetic component at all, then they wouldn't be able to just "choose" to be (or not be) gay. You can't just choose to change your hair color or height halfway through your life lol.

You obviously aren't able to critically think about the implications of your claims. . so I'm sure I'm just wasting my time trying to explain these examples.

Firstly sexuality is a spectrum, it doesn't matter that you don't like it's implications, this is what any study into human sexuality has found. Some people like only men, some men a little bit and women lots, others like men lots and tentacle monsters and japanese school girls loads. There are as many sexual preferences in the world as their are people, ranging from one extreme to the opposite. That is a spectrum. No one in their right state of mind would say that emotions do not play a role here, but genetics could very easily be a factor too. I hope you can appreciate how ridiculous it is for you to absolutely insist that genetics cannot be a factor because there is no evidence to support it, whilst touting the alternative with absolute certainty despite its having the same inherent default.

You're getting into psychology here. . which I hate break it to you, is not science. This "spectrum" you speak of is entirely subjective and there is no reliable way to measure it.

It is a conceptual idea that exists in our heads only. . not objectively. There are also similar "spectrums" of love, hate, anger, virtually every emotion you could think of has a "spectrum." That certainly doesn't make it science. And oh yeah. . Ahem, ever heard of the "self-reporting problem" ?

Basically you haven't made on reasonable suggestion so far in this thread. If you want to offer an alternative view point then trying adding some actual evidence, don't just insist the hardest that you are right others are wrong/

Here's a reasonable suggestion: Do the research for yourself and be skeptical. Require more than just a few correlations from pop studies to formulate your understanding of science. There's a lot of bullsh*t out there, and unfortunately you have fallen head first into this steaming pile of it.

I can't speak for the OP but I'm sure he had heard about a genetic link to sexuality, since asked about one.

 

 

"Sure, not all sex leads to babies. But it DOES NOT FOLLOW then that not all babies come from sex! Well maybe test tube babies"

Congratulations! you have realised that life is slightly more complicated than

1 cause=1 effect.

You continue to misinterpret the facts and you are now putting words in my mouth, albeit they are irrelevant to the point at hand anyway. At no point did I say that 1 cause = 1 effect. . .somehow you have falsely interpreted this. I said that homosexuality is not genetic. Sure, I will venture as far as to say that I speculate it is caused by the interaction and presence of a number of environmental factors. But that is as far as I (and anyone else) can possibly go at this point. No one knows for sure which factors these are and why they produce such results. Genes are responsible for your eye/hair color, skin type, height, etc. but NOT for your behaviors like homosexuality, narcissism, depression, etc. Why is this so difficult to grasp?

Now you need to apply this to the case of human behaviour (which is very complicated).

 

 

A single gene cannot, on it's own determine eye colour, (in spite of what you said earlier).

Similarly there is no single "gay gene".

However there are genes related to sexual preference.

Okay, let me better illustrate for you the fallacy of your argument, since you have raised it twice to no avail. I did specifically point this out in my post earlier, but you've obviously missed it so I'll do it again. . .Of course no gene can determine anything on its own, it would be silly to assume so. But that doesn't change the fact that there are particular genes responsible for particular features.

Take a television for example, when it is being manufactured. The 'color chip' (component which gives color to the picture) is of course useless by itself, but without it the TV would be black and white. Add the component and you have a color picture. In the same way, genes are of course useless by themselves, that was never the issue here, but that doesn't mean that a particular gene can't be responsible for a particular feature.

But, when it comes down to it, there are clearly researched associations between genetics and sexual preferences.

The keyword here is "associations." Many junk studies show associations all the time, but that doesn't merit their validity. I see rubbish like this in the media all the time - "Gene thought to be linked to suicide" is a particular silly example I remember seeing somewhere a while back. Quite frankly it is troubling to see how they manipulate the general public's ignorance of science when it comes to such articles. It is very important to know that associations and correlations are relatively insignificant without a unifying theory. .like I said earlier, theories are everything in science. Without one (that can be reliably reproduced time and time again to come up with the same results), you really don't have science.

" The plausibility that homosexuality has any genetic origin at all is about equal to the plausibility that the flying spaghetti monster rules the universe. "

OK, explain the correlation please.

I have already explained the analogy earlier, but I will again. You are making a claim here - the claim that homosexuality has (at least in part) a genetic component. Homosexuality is well known to be a behavioral trait. . not a physical one like the previous examples of genetic expressions such as eye color or height. There is ample evidence to prove that these expressions (eye color, height, etc.) indeed are genetically predetermined, so I do not challenge this. But your claim, however, lacks ample evidence. There are no tests which are reliable enough to be done time and time again to yield the same results to prove your claim. To compound this problem, you have put forth the notion that you can't "exclude the possibility" of your claim simply because there isn't solid supporting evidence. So in other words, you are saying to me "You can't prove that homosexuality isn't genetically predetermined, therefore my claim is still valid." This is where you exit the realm of science and testable theories and into the realm of untestable philosophical debate. Just as I can't prove that the flying spaghetti monster doesn't exist, neither can I prove that homosexuality isn't genetic. . .but the evidence still strongly points in the opposite direction in both cases.

Also, why is there more association between sexual preference of identical twins than between fraternal twins?

Read this. . .

Homosexual Twin Studies

Two American activists recently published studies showing that if one of a pair of identical twins is homosexual, the other member of the pair will be, too, in just under 50% of the cases. On this basis, they claim that "homosexuality is genetic."

But two other genetic researchers--one heads one of the largest genetics departments in the country, the other is at Harvard--comment:

The author of the lead article on genes and behavior in a special issue of Science speaks of the renewed scientific recognition of the importance of environment. He notes the growing understanding that:

Do you think a tendency to heterosexuality is genetic?

No, sexual orientation is a non-Mendelian trait. This is a crucial part of the point.

If not how do animals know whom to mate with?

Are you asking how animals know to mate with with members of the opposite sex? This can only provoke speculation, as we are unable to understand the psyche of animals.

There is no "brown eye" gene ( except in elementary level text books).

Even wiki has a better grasp of it than you. The wiki page clearly says "The genetics of eye color are complicated, and color is determined by multiple genes."

Flawed argument. Sure, everything about our physical (not behavioral) characteristics are governed by the interaction of multiple genes, not just eye color. But this doesn't change the fact that an individual must possess a specific gene to have a specific feature. If you completely lack the gene(s) for brown eyes, then you will not have brown eyes. This really is a very basic concept, you've even said yourself that it is "elementary textbook" stuff. So I'm surprised that you aren't grasping it then, lol.

Everybody except one does. You are that one.

You mean me and the original poster. Yeah, we must be the only ones in the dark. . .

By that argument, sex isn't the cause of children.

Not all sex leads to children (and according to some minority views, not all children were caused by sex- but that's another issue).

No.

Sure, not all sex leads to babies. But it DOES NOT FOLLOW then that not all babies come from sex! Well maybe test tube babies

In fact I'm not even sure what twisted logic you've used to arrive at that preposterous conclusion. . but it is indeed another fallacious argument. The rule I quoted (which every decent scientist is familiar with) is the concept that if you OBSERVE a single black swan then you know that not ALL swans are white. Have you ever OBSERVED (or heard through reliable documented reports) of human babies coming from any source other than human sperm/egg fertilization? Didn't think so.

If you did though, that would be your 'black swan.' If you for example witnessed an elephant giving birth to a baby human, it would then be safe to say that not all human babies come from humans. But man, you were way off lol.

Hope you can see the massive contradiction in your argument here dude. It is still entirely plausible that homosexuality has a purely genetic explanation, just one that is too complex for us to understand directly. Sexuality is a spectrum after all so we could be looking at a whole list of differences in genes that takes us from purely homo to purely hetro. The truth is we just don't know, like you say ''it is a largely unexplainable phenomenon'' (at least given what we currently know. So how then do you justify going from sexuality is inexplicable to providing an explanation for it all in a single line then lol.

There isn't any contradiction in my position at all. The plausibility that homosexuality has any genetic origin at all is about equal to the plausibility that the flying spaghetti monster rules the universe. We don't need any proof for that either. . and it sure is convenient to just say for now that "it is too complex for us to understand directly."

Also, sexuality is not a spectrum. .this is just your perception. Sexuality is based on emotions. . .and those emotions change from person to person for different environmental reasons, but they are never genetic. Take a minute to think about the implications of what you are proposing: A behavior (homosexuality) is caused by a gene. If this were true, then it would have to follow that there would be genes for every behavior. . like homicidal genes, kleptomania genes, intelligence genes, etc. It just isn't true. . .

From Science, 1994:

Two things:

1) Since when is "genetic" the same as "a single gene"? By that argument there is no evidence that species membership is genetic.

Um, yes it is. If you have brown eyes for example, that means you have the specific "brown eyes" (dominant) gene. The question then follows that if homosexuality is

"genetic" (which it isn't), then homosexual people would possess such a gene. The problem is that homosexuality is a behavior and not a physical trait.

2) If homosexuality isn't genetic, than how come it in fact is largely genetic? http://www.tim-taylo...es/studies.html

Wow, pretty bad science. At best, you have some correlations in these (outdated and limited) studies, but no causation whatsoever. Trust me, if it was discovered that

homosexuality was indeed genetic, everyone would know about it by now!

Although it is debatable, Xq28 is a gene that has been thought to be linked to homosexuality.

Once again, correlation not causation. And never forget a cardinal rule of science. . "it only takes the sighting of one black swan to know that not all swans are white."

In other words. . .this Xq28 gene you speak of, if there is a single straight person who possesses it, or conversely a single homosexual person who lacks it (which I'm sure there are), then you know that this gene can't possibly be responsible.

It's been explained to you plenty. It's because we ignore 99.9% of our DNA when doing that test, and focus on that 0.1% that is different.

It hasn't been explained at all. Think about what you're saying. How can Sub Saharan African DNA be "ignored" if it is one of the categories ('differences' as you put it) which are being tested for? If it was being ignored, it wouldn't even be on the test! I think what you're failing to see is that it is within this 0.1% that the differences exist...

I haven't read everything in this thread, but I just wanted to offer a fast reply to the original poster's question: Is homosexuality genetic?

The answer is: NO

There has never been any conclusive (or even suggestive) scientific evidence to my knowledge that would imply that homosexuality is triggered

by the existence or lack of a specific gene. It is largely an unexplainable phenomenon...but it has everything to do with environmental conditions

and influences and nothing to do with genes.

And we do. We just ignore it for the test in question. Looking at similarities doesn't help you tell the difference.

No, we don't. . .which is why I originally made the post. We don't always find the Sub Saharan African DNA in individuals, when theoretically we should.

Some people show up 0% Sub Saharan African. Why this occurs has yet to be explained.

How are the Selachimorph any older than us Teleostomi? We were both Gnathostomata before we went our separate ways (and we still are). Of course species Homo sapiens is more recent than superorder Selachimorph. But I bet there's newer shark species than Homo sapiens. And certainly any shark species of your choice will be younger than us Teleostomi.

I'm certainly not an expert on sharks, but I don't have to be to know that some species of shark evolved hundreds of millions of years ago...and that our species isn't anywhere near that old. Therefore, we are newer species in comparison.

Well said NTett, I fully agree that the more newly evolved genetic frequencies aren't any "better" or "worse" than the older ones...this isn't the question at all here. Nor am I on any sort of racist agenda trying to prove genetic purity or dominance.

With regards to the Chimp example: of course this is a bit extrapolated, since I am comparing different species (chimps and humans) to varied members of the same species (African Vs. European). And you are certainly right in your points, I should have worded it better. The 98% similarity in DNA between humans and chimps is what we have from our common ancestor; in other words, we didn't evolve directly from chimps. But even then, the point here is that we are expecting to see this 98% similarity when we test any two chimp and human subjects. . just as we would expect to see some traces of Sub Saharan African DNA leftover in any two different humans tested. . .

Nope! The whole concept of one contemporary species being "newer" or "superior" to another goes against everything evolution says, and is reminiscent of the ancient Greek and Lamarkian ideas of a Great Chain of Being. One species may be closer to its ancestral species but that does not make it any worse nor better. You cannot ever tell by comparing two individuals which is closer to the ancestral species. To be able to claim similarity to a common ancestor would require either comparison with several other current related species or with fossils from the ancestral ones.

The "concept" of a species being newer (I never used the words 'better' or 'superior') is not a concept at all, it is a fact. Sharks for example, are much much older than humans. Our species' genetic origins only have their roots dating back to about 500,000 years ago. . .this is most definitely "newer" when compared to any given species of shark for example. You are right however, that you can't ever be 100% sure that any given species is genetically closer to its ancestral species. . but in some cases there is considerable archaeological/fossil evidence to support it.

Okay, let me back up a bit here... and thanks for chiming in too Ntettamanti.

I of course understand that all living things have DNA. And I also understand perfectly that these "ethnicity" tests are ultimately

just tests which look for gene frequencies that express different variations among members of our species, homo sapien sapien.

And yes, I also understand that the tests are looking for differences rather than similarities, otherwise the whole purpose of the

tests would be defeated.

Now with that being said, let me illustrate my point through an example:

The first humans came onto the scene in Sub Saharan Africa, then large groups of this original blood line migrated to Asia and Europe.

These groups settled in and evolved over time, procreating and passing on new mutations/dominant genes which resulted in a

group of people who eventually looked significantly different from their original group in Africa. Now of course the "original" group

in Africa, who never migrated, didn't stop evolving or stay stuck in time genetically. However, they still retain much more of the original blood line

(referred to as "Sub Saharan DNA") than the groups who migrated off. . .

At this point, how could you expect one of the direct descendants of the original group to have any of the more newly evolved genetic

frequencies that show up in the groups who had migrated? Another example is with humans and chimps:

We share 98% of our DNA with chimps. . .that other 2% is what makes a very large difference in terms of our physical features and brain

capacity. Now, we know that chimps are "further back" on the evolutionary tree than humans. . they are closer to the common ancestor than we are; or in other

words, our species is newer because it came into existence more recently.

So it follows then that you would expect to find "chimp DNA" in human tests. . .but you would NEVER find that other 2% ("Human DNA") when testing a Chimp!

Time only moves forward, never backwards. . .

There's no need to travel back a million years, or even a few hundred thousand. There are many "modern" African people who show nearly 100% Sub Saharan DNA on their test results. . .this is what i refer to as "old" DNA and indeed why I put it in quotations. Obviously, it isn't frozen in time, but these people are closer genetically to the first humans on the evolutionary tree than any European/Asian/Native American person. . and therefore it would be surprising to find "European DNA" in their test results. However, it should then follow that this Sub Saharan African DNA SHOULD be found in ALL other humans. . unless of course the tests are not accurate enough to encompass such a long time period and the genetic frequencies have been greatly diluted (which I believe to be the case).

Think of it like this. Suppose you have a species of flower that can have red, white, blue, and purple flowers. Then someone takes the wild population and divides it into groups based on the color. Later on, you could do a genetic analysis of the DNA and determine which group an individual plant belongs to (or you could just look at the color). However, that grouping was rather arbitrary, and you could as easily grouped them by height, pest resistance, seed size, or whatever other attributes you can think of. Racial genetics is rather like this, but not so much based on specific genes that either exist or not in a population, but rather the frequency of an enormous range of genes. One assortment of gene frequencies we call "african", another "european", "asian", or "native american". You could take any of these populations and through careful breeding change the gene frequencies to match those of another race, unless there are some genes unique to any one group, but that would take a very long time. Because so many genes are involved, for quite a while it would be possible to identify the proportions of the groups which form your ancestry.

 

Another example would be if you had four children. One of your children stayed at home and the rest went each to a different continent, and all had children of their own. By DNA testing you can tell which of your children the grandchildren belong to, even though they are all descended from you. You could also tell that one of the grandchildren was not the son of your stay-at-home son, which of course should be no surprise.

 

So humanity divided from its common origins into a few groups each of which went their separate way genetically with low intermingling. It should no more surprise you that the tests might show no african ancestry in an euoropean than if it shows no euoropean ancestry in an african, since all are from a common origin.

Mr. Skeptic,

Thank you very much for the reply, however I don't think that you really addressed the question... I am aware that certain gene frequencies are what comprise the "categories" if you will (like Sub-Saharan African or European), but the question is: "WHY is the Sub Saharan African gene frequency completely absent from the DNA tests of certain individuals, if all humans descended from ancestors in Sub Saharan Africa?"

Your last statement particularly troubled me. . .

It should no more surprise you that the tests might show no african ancestry in an euoropean than if it shows no euoropean ancestry in an african, since all are from a common origin.

African ancestry should show up in all humans theoretically, but the reverse is NOT true. Why would you expect to find European ancestry in an African person's DNA if they come from a family line that never intermingled with (the more newly evolved) European people? The European DNA is "newer" in the sense that it evolved later in time, and so theoretically you wouldn't expect to find traces of it in the "older" Sub Saharan African DNA.

First off hello everyone, I am glad to have joined this forum and look forward to being a contributing member here.

My first post is regarding the "DNA ethnicity tests" that many have probably heard of already. These tests analyze your DNA and as

far as I have seen, provide results which are traceable ultimately back to 4 major categories: Sub Saharan African, European, Asian, and

Indigenous/Native American. What got me thinking was a show that I had seen a while back on PBS, which featured a bunch of well known

stars who had these DNA tests ran on them. Many were surprised by the results, which often included categories that they didn't suspect

(I specifically remember A Mexican actress who was rather shocked to learn that she had deep Asian roots). What I noticed was, that some

people who were tested had 0% Sub Saharan African in their ethnic makeup. How could this be if we all originated in Africa? I don't doubt that

the human race did indeed originate in Africa, but it does seem a bit strange that some people exhibit no traceable lineage back to it; shouldn't we

all theoretically have a little bit of "African DNA" in us? How is this possible? Is it just that the DNA is so diluted by now that it simply doesn't

show up anymore using the current test methods?

Any thoughts?

Cheers.