Parental Wealth is Pop Strat

 This paper discusses how parental wealth is a strongly prone to assortative mating. 

...parental wealth homogamy is high at the very top of the parental wealth distribution, and individuals from wealthy families are relatively unlikely to partner with individuals from families with low wealth. Parental wealth correlations among partners are higher when only parental assets rather than net wealth are examined, implying that the former might be a better measure for studying many social stratification processes. Most specifications indicate that homogamy increased in the 2000s relative to the 1990s, but trends can vary depending on methodological choices. The increasing levels of parental wealth homogamy raise concerns that over time, partnering behavior has become more consequential for wealth inequality between couples.

The reason this is important in terms of genetic studies, is that it creates population stratification that will no doubt present itself as genetic correlations, giving the impression that genes exist for income (yes such studies have been done), as well as other things like educational attainment, when all that is really happening is that the rich are keeping it in the family, so to speak.  They noted that it was less common, but still an issue in Denmark, where the study was done, but worse in other countries (US and UK, for example). Thus these GWAS that purport to show such genetic correlations are likely really demonstrating that certain social/ethnic groups have an unfair proportion of wealth. By this token, if you were going to use "polygenic scores" for educational attainment to decide who should get into an elite school, it would more fair for those with the lowest scores to be given preference...

The Tarot of Reading Neuroimaging

 I'm linking to this piece discussing the lack of consistency among researchers reading and interpreting Neuroimaging studies, because I think this highlights why it is akin to phrenology or perhaps Tarot card readings. 

 Research Teams Reach Different Results From Same Brain-Scan Data 

 "When 70 independent teams were tasked with analyzing identical brain images, no two teams chose the same approach and their conclusions were highly variable. "

The fact that these are static neuroimages gives the impression of some sort of consistent, definitive interpretation. But Tarot Cards are also the same deck no matter who is laying out the cards. "It's in the cards," they will say. But, in truth, it is in the card reader. 

 

Another Recent Study that is Consistent with my Third Law

 Since I usually focus on genetic studies, I wanted to highligtht more "Behavioral neuroscience" studies since this seems to be the fallback for the failure of genetic studies to deliver. This preprint study debunks some of the male/female brain disparity stuff. 

Dump the “dimorphism”: Comprehensive synthesis of human brain studies reveals few male-female differences beyond size

Here is the money quote from the abstract:

 In sum, male/female brain differences are non-binary and trivial relative to the total variance across human populations. Properly speaking, the human brain is not sexually-dimorphic.

 That we still have to debunk phrenology, just because it's repackaged in the form of MRI's is hard to fathom. I understand that one might argue that MRI ostensibly measures brain size and traditional phrenology measured the skull with implied brain size differences. But is the reason phrenology is mocked, because skull bumps don't properly measure brain bumps, or is it because measuring brains itself is folly and invariably clouded by the racist (or in these cases, sexist) biases of those doing the studies? 

Again, I'll put my Third Law of the Behavioral Genetics Fallacy here:

Differences in human behavior, intelligence and personality are not accounted for by structural or functional differences in the brain.

Another Study that I Think Illustrates my Third Law of the Behavioral Genetics Fallacy

This study points out some of the (many) limitations of fMRI studies or what they refer to as Brain-wide Association Studies:

Towards Reproducible Brain-Wide Association Studies

The operative word here is "towards," since such studies approach, but never seem to achieve, reproducibility. They are inherently flawed, both in the tarot card method of reading them and simply because they are trying to capture something that doesn't exist. I'll lay down my Third Law of the Behavior Genetics Fallacy again:

Differences in human behavior, intelligence and personality are not accounted for by structural or functional differences in the brain.

In this particular study, they point out the limitations of low N studies of this nature:

 In smaller samples, typical for brain-wide association studies (BWAS), irreproducible, inflated effect sizes were ubiquitous, no matter the method (univariate, multivariate). 

The implication here is that larger N's will start to produce replicable results. Again, this has been the shell game for decades. What can we say about all the studies that were previously touted in this genre and are now shown to be defunct, like a dead salmon (ht Ben from Twitter).

Good Illustration of My Third Law of the Behavioral Genetics Fallacy

 This study is a good example of my Third Law of the Behavior Genetic Fallacy:

Differences in human behavior, intelligence and personality are not accounted for by structural or functional differences in the brain.

 The lengthy title of the study captures it, I think:

Hippocampal grey matter tissue microstructure does not explain individual differences in hippocampal-dependent task performance

This study used MRI's to measure hippocampal size and then see if a bigger hippocampus correlated to "...scene imagination, autobiographical memory recall, future thinking and spatial navigation..." which "... have long been linked with hippocampal structure in healthy people, although evidence for such relationships is, in fact, mixed. " Well, mixed no longer, I hope. Nevertheless, there was an illusion of "evidence" up to that point, where one could tout such nonsense as fact. This is what I like to call the shell game of false positives, in which a study purports to show something, does not replicate, but by that time, they have some new studies to hang their hats on. 

People don't need a big hippocampus. The idea is ludicrous on its face and the use of MRI's to measure brain sizes is little more than high tech phrenology.

 

 

Music as an Analogy to my "Fourth Law" of The Behavioral Genetics Fallacy

 In a previous blog post, I laid a rationale for what I referred to as the Four Laws of the Behavioral Genetics Fallacy (In contrast to the Three Laws of Behavior Genetics of Eric Turkheimer). In reference to my fourth law, I briefly used music as an analogy. I wanted to expand on that analogy, a bit here. First, here is the fourth law:

Advancements in understanding human behavior and psychology require inner exploration from the scientist, the subject or both.

This idea will probably rub a lot of traditional scientists the wrong way. Generally, it is considered unscientific and too subjective to include the observer with the observed and psychology researchers try to maintain a passive detachment from what they are studying, otherwise it would give the impression of bias. The problem with this is that it assumes that psychology can be studied in an purely objective manner, whether that be by recording observations or analyzing genetic or neurological processes, with the expectation that that would somehow give us a better understanding of psychological processes. 

It might be uncomfortable to acknowledge this,

My Four Laws of the Behavioral Genetics Fallacy

 I discussed these in more length, here as a response to Eric Turkheimer's Three Laws of Behavior Genetics. But just wanted to lay them out in one short post (credit Turkheimer for the second, which is his third).

My Four Laws of the Behavioral Genetics Fallacy:

1. Any behavioral trait studied within a society will be correlated genetically to specific subpopulations, regardless of whether these genetic correlations are directly related to the trait.

2. A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families.

3. Differences in human behavior, intelligence and personality are not accounted for by structural or functional differences in the brain.

4. Advancements in understanding human behavior and psychology require inner exploration from the scientist, the subject or both.

Some Comments on "The Three Laws of Behavior Genetics" (and the two other laws)

Twenty years ago, Eric Turkheimer wrote an often cited paper titled:

Three Laws of Behavior Genetics and What They Mean

This paper is still often cited today and perhaps has taken on a life of its own, with a more deterministic interpretation than Turkheimer apparently intended and for which he recently clarified in a blog post his original intent. Nonetheless, much of the criticism of his paper comes from those in the genetic determinism camp, with the extremes being the "race scientist" crowd. So, since I sit on the other end of the see saw from the genetic determinists with Turkheimer poised somewhere in the middle, I will weigh in with my own thoughts about his three laws, as well as the two additional non-Turkheimer laws added into the soup. In the process of this, I will posit my own Four Laws of the Behavioral Genetics Fallacy. First, let's lay out the three laws that Turkheimer posits:

First Law. All human behavioral traits are heritable.

Second Law. The effect of being raised in the same family is smaller than the effect of genes.

Third Law. A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families.

I agree with perhaps one and a half of these laws. I’ll start with my half agreement with the First Law. For starters, I take issue with the use of the term “heritable,” because the term predates genetics and has had many different meanings and interpretations over the years, as this article points out:

The term ‘heritability,’ as it is used today in human behavioral genetics, is one of the most misleading in the history of science. Contrary to popular belief, the measurable heritability of a trait does not tell us how ‘genetically inheritable’ that trait is. Further, it does not inform us about what causes a trait, the relative influence of genes in the development of a trait, or the relative influence of the environment in the development of a trait.

Genetic Prediction of Schizophrenia via Polygenic Risk Score Has No Clinical Utility

 A new study from Schizophrenia Bulletin tested various risk factors on a group of individuals in a Netherlands. In addition to other risk factors, they used Polygenic Risk Score (PRS) developed from previous studies. This summarizes the results:

We calculated the relative contribution of each (group of) risk factor(s) to the variance in (change in) mental health. In the combined model, familial and environmental factors explained around 17% of the variance in mental health, of which around 5% was explained by age and sex, 30% by social circumstances, 16% by pain, 22% by environmental risk factors, 24% by family history, and 3% by PRS for schizophrenia (PRS-SZ). Results were similar, but attenuated, for the model of mental health change over time. Childhood trauma and gap between actual and desired social status explained most of the variance.

 This is a weak result all around, but particularly bad was the PRS which had a predictive success of 0.5 % (3% of 17%). Thus, just knowing a person's age and sex was almost twice as predictive as the PRS. If the person had a history of pain or other medical complaints, that alone was 4 times more predictive for schizophrenia. This is simply a dismal failure and the continued hope that this will be good enough to be clinically useful is little more than wishful thinking. Realistically, to be clinically useful, it would have to be 25 to 50 times better than this and I am guessing it has come close to peaking.

Yet More UK BioBank Pop Strat Issues Noted.

 There are so many studies coming out noting population stratification issues that it is hard to keep track. This is an interesting preprint looking at CAD and BMI:

Fine-scale population structure confounds genetic risk scores in the ascertainment population

From the Abstract:

we investigated the accuracy of two different GRS across population strata of the UK Biobank, separated along principal component (PC) axes, considering different approaches to account for social and environmental confounders. We found that these scores did not predict the real differences in phenotypes observed along the first principal component, with evidence of discrepancies on axes as high as PC45. These results demonstrate that the measures currently taken for correcting for population structure are not sufficient, and the need for social and environmental confounders to be factored into the creation of GRS. 

One interesting aspect of this study, I think, is that it highlights how it can be necessary to have a good working knowledge of the population you are studying.  This plot is striking in that respect:

This was confined only to white European descent, but still had this kind of stratification. A larger point here is that more and more pop/strat issues arise, many of which were not accounted for in earlier studies and perhaps should lead to corrections. Moreover, for those doing GWAS in the future, particularly in the UK BioBank, it is worth having a bit of skepticism that at least some of what you are seeing is pop/strat that has yet to be recognized.