Tuesday, May 19, 2009

More on Rex and genes

Some more on my debate with Rex. He has already moved towards admitting that genetics does play a role, but still thinks that the non-genetics part must be social environment. So lets move him a bit further away from this stance.

>>>The figures suggest that genetics plays a role, but identical twins are (as the name suggests) identical, so their parents treat them in identical ways, and their environments are usually identical. However, the figures also indicate that environmental factors play a very significant role. If stuttering were purely genetic, there would be 100% concordance among identical twin stutterers ... but there isn't!

No no no.

First, if genes can cause or contribute to stuttering, that means that physical stuff can cause or contribute to stuttering. And therefore, it is very likely that non-genetic physical stuff like brain trauma or virus infection striking in the same functional regions as the genes, will also cause or contribute to stuttering. So the proof of genetical influence very often indicate that other physical may also cause or contributors! You cannot say: Oh genes is 40% so social environment is 60%. Only that "other physical causes" and "social environment" equals 60%! Where social environment can run from 0 to 60%!

Second, the twin studies do not show that environmental factors play a significant role. It only shows that non-genetics factors play a role. It is a commonly made mistake to attribute non-genetics factors to parental skills (the nurture part) exclusively.This attitude comes from the flawed nature-nurture view. A vast majority of non-genetic influences do not come from parents or social environment, but from random events like pre-natal events, accidents, illnesses, trauma. Then most impact from their social environment come  from the influence of their peers and from school. Kids spent the vast majority of their time with their peers, their school teachers. Relatively little with their parents. And even parental influence is not uniform for both twins. Kids can react very differently to parents. I am not saying parents play no role, but with increasing age less and less, and at very early age kids are not social beings but more like animals.


>>> The scientific literature that you cite is just a rehash of what has been done for decades. Nothing new has been found. The same questions that were asked 30 years ago are still being asked today ... zero progress.

I gave links to review articles for laypeople. There has been a lot of progress on empirical findings but the full picture will be quite complex.

And there is recent research. For example, I also cited the very recent and large scale (1000s of twins):

Am J Speech Lang Pathol. 2007 May;16(2):169-78. Genetic etiology in cases of recovered and persistent stuttering in an unselected, longitudinal sample of young twins. Dworzynski K, et al.

But here are others:

Am J Hum Genet. 2006 Apr;78(4):554-63. Epub 2006 Feb 1. New complexities in the genetics of stuttering: significant sex-specific linkage signals. Suresh R, Ambrose et al.

J Fluency Disord. 2007;32(1):33-50. Epub 2006 Dec 30. Genetic studies of stuttering in a founder population. Wittke-Thompson JK, Ambrose N, et al.



>>>> My understanding is that the stuttering researchers are of an embarrassingly poor standard ... and something tells me that you agree with me.

I agree with you, but not for genetics and brain imaging. ALL the scientists who work in these areas are professional scientists. Most of them are not outstanding scientists, but they apply the standards of their fields well.

4 comments:

Rex said...

Tom,

I'm sorry to say it because you seem like a nice guy, but you are sinking to new lows.
You said:
"He has already moved towards admitting that genetics does play a role, but still thinks that the non-genetics part must be social environment."

I never said that genetics doesn't play a role. And I never ever used the words "social environment". Environmental factors include many things - external environments, such as parents, schools, traumatic experiences. But they also include *internal* factors - such as genes affecting other genes.
Of course genes plays a role ... you are full of genes, and one may even argue that your genes indirectly made you become a physicist or made you create this blog. But such an argument is flawed because you are not defined by your genes alone. Had you been taken away from your parents after birth and raised in a jungle, you would never be thinking about the possibility of sterile neutrinos interacting with Higgs bosons causing neutrinos to have mass, or playing a Nimzo-Indian. Or, had you been hit in the head when you were little, causing brain damage, your life would have turned out very differently. This is what I mean by "environmental factors", and that is the way geneticists use the word.

You also wrote:
"Second, the twin studies do not show that environmental factors play a significant role."

Of course they do play a significant role - for the very reasons I describe above. Let's forget about stuttering for the moment. Take 2 twin embryos. They do not share identical environments (experiences) in the womb and they do not share identical environments (experiences) outside the womb when they are born. That's why they are different and individual, even though they have identical genes. The studies I cited show that environmental factors play a very significant role; as a stutterer, this is obvious to me even without studies.

In your responses to me, you have totally misunderstood my arguments, and I don't know if that was intentional or not.

Now, as for the competency of the researchers. You wrote:
"ALL the scientists who work in these areas are professional scientists. Most of them are not outstanding scientists, but they apply the standards of their fields well."

I do read some of the papers occasionally, and I find them of very poor standard compared to the papers in other scientific fields - and I know you do too. In the past 10 years, most of the brain imaging studies related to stuttering appear to be of the type "let's compare a stutterer's brain with a fluent person's brain and let's see if we can find a discrepancy". Such approaches lead nowhere. Genetic studies are almost as ridiculous. For example, I participated in a genetic study 5 years ago at a stutterer's convention. They presumeably compared my DNA (and those of other attendees) with normal DNA in order to find discrepancies. A couple of years later, we got the results ... which was as I had expected ... no result. What were they trying to find? A stuttering gene? a gene that directly causes people to stutter? They'll never find such a thing. They don't appear to realize that stuttering is most probably multi-factorial and can have different root-causes - just like baldness ... two bald people may look similarly bald, but the causes of their respective baldness is totally different.

But you don't need good old Rex to tell you these things. The results of decades of stuttering research speak for themselves.

Now, let's see how you distort my arguments this time :)

KJ said...

Hey Rex, Tom said stuttering is Not Multi-factorial.

Hey Tom, why are you bald? What are the causes of baldness, thought it was caused by genetic...sure baldness can be due to stress and other health reasons. But for the majority of the people...genetic??

Rex has a point...

But what is wrong with:

"let's compare a stutterer's brain with a fluent person's brain and let's see if we can find a discrepancy".

PK said...

I totaly agree with Rex, and I do see that Tom has been misrepresenting his arguments.

Comparing a stutter's brain with a non-stutter's brain leads to a dead end because the very fact that a person stutters for years and years has an affect on the brain. Just like a person who plays the piano for years has a differnt brain structure than a person who doesnt. But it doesnt mean that the pianoplayer was born with that brain structure

KJ said...

Okay, so we take into account neural plasticity. What is wrong with understanding the effects of stuttering on the brain over time?
Seems like a good research project/question.

Look at a stuttering brain from baby to age 5 to age 10 to adult.

Tom will have to respond to the misrepresenting part.