Newsletter #004: Behavioral Genetics
Heritability and Etiology from Jonathan Egeland; genetic confounding by Alexander Kruel; high heritability and interventions from Emil Kirkegaard; heritability and malleability from Neven Sesardić
Heritability and Etiology: Heritability estimates can provide causally relevant information (2023) by Jonathan Egeland. Heritability tells us something about causation.
Can heritability estimates provide causal information? This paper argues for an affirmative answer: since a non-nil heritability estimate satisfies certain characteristic properties of causation (i.e., association, manipulability, and counterfactual dependence), it increases the probability that the relation between genotypic variance and phenotypic variance is (at least partly) causal. Contrary to earlier proposals in the literature, the argument does not assume the correctness of any particular conception of the nature of causation, rather focusing on properties that are characteristic of causal relationships. The argument is defended against Lewontin's (1974) locality objection and Kaplan and Turkheimer's (2021) recent critique of Genome-Wide Association Studies (GWAS).
Genetic confounding by : Kruel links to 20 studies that point to the importance of genetic influence:
80% of today's wealthy Chinese are descendants of pre-communism elites
Descendants of 18th-century Hungarian nobles disproportionately held privileged positions throughout 20th century Hungary despite transitions into and out of Communism.
Destruction of parental wealth via the American civil war had only a very weak effect on offspring income (a 0.4% decrease in income per 10% decrease in parental wealth).
A (gruesome) natural experiment in the Soviet Union shows the inter-generational persistence of educational levels: The descendants of people forcedly resettled to the Gulags are more likely to be educated and areas around camps more prosperous.
Land lottery in Georgia (1822): Family lines of men who won land were no better off than those of non-winners.
High heritability does mean that social interventions likely won’t work well by : Equalizing environments will not give large returns on highly heritable traits. Social programs that aim to equalize an environment for something highly heritable, like intelligence, will not achieve equal outcomes. Furthermore, a substantial portion of the environmental influence on intelligence is either due to measurement error or randomness. It is conceivable that we could discover some unknown intervention that works incredibly well at boosting intelligence. However, since many interventions have been tried without success, we have good reason to be skeptical of new interventions. On the final point about possible interventions, Kirkegaard says:
I think this error of reasoning is another example of the deductivist fallacy. The deductivist fallacy is when one can prove mathematically or logically that one fact has no logically necessary connection to another fact (i.e., it is not self-contradictory to claim both). However, just about everything in science is actually about probabilistic reasoning, not necessity. Thus, while it is true that a high or perfect heritability for some phenotype does not logically rule out every imaginable intervention we might try, it does make them unlikely to work or at least be effective. That's because almost all interventions, and probably all large-scale social interventions, involve equalizing some aspect of the environment that already varies between families, and thus is already included in the 5% shared environment component. If people who support interventions want to get serious, they need to start proposing interventions that change some aspect of the environment that doesn't already substantially vary between families. Everything already varies a lot between families! What is there really to try that we haven't tried already?
Making Sense of Heritability (2005) by Neven Sesardić: This is an excellent book. Kirkegaard quotes from it in his above article. Sesardić is a philosopher who addressed a very large number of attacks on the concept of heritability. Chapter 5 is entitled “Genes and Malleability.” It addresses the relationship between the ability to mold a person’s phenotype and their genes. Similar to Kirkegaard’s point in the quote above, many interlocutors or opponents of behavioral genetics use absolutist language. They say that people like me are “genetic determinists” or believe certain traits are “innate” or “inherent.” This is a misunderstanding. Another example of this sort of language Sesardić addresses is the charge of believing certain traits are “immutable”:
We would be completely baffled if someone criticized the statement that Alzheimer’s disease is incurable by saying that certain effective, though presently unknown, interventions might become available some day. Of course they might! Who would deny that? Surely, the word “incurable” does not mean “something that has no cure now, and is bound to remain without cure in all eternity and in all possible worlds.” If, per absurdum, it did mean that, the word would be totally useless.
But those who object to the claim that heritability constrains malleability often commit the same mistake of replacing the context-relative and only meaningful way of discussing malleability or modifiability with a trivially true but irrelevant statement that heritable traits are not absolutely unchangeable. Here is an example how the debate is muddied by introducing an unnecessarily strong word, “immutability”:
There continues to be a popular but mistaken belief that the level of heritability equates with the ease or difficulty of changing or altering a particular characteristic, or its immutability. However, researchers in behavioral genetics and psychologists would now agree that the ways in which different factors interrelate in the development of a characteristic are not related to its immutability. (Nuffield 2002: 21 – italics added)
Notice how the sensible question whether the level of heritability is related to “the ease or difficulty of changing a particular characteristic” (to which one might well be disposed to give the answer “yes”) quickly shifts to, and is indeed replaced by, a pseudo-issue of “immutability.” Difficult to change? Perhaps yes. Currently unmodifiable? Again, maybe yes. But immutable? Of course not! (Sesardić, 2005, p. 164)
My newsletters contain links, articles, and papers that remain relevant. If you enjoyed this, consider taking a look at previous newsletters:
Newsletter #001: Cognitive Ability — Independent intelligences as a degenerating research program; against IQ threshold effects; the IQ halo effect; and IQ fadeout
Newsletter #002: Genetic Enhancement — The most important works on embryo selection for IQ (Shulman, Bostrom, Branwen); the utility of polygenic screening from Karavani et al.; genetic architecture of intelligence from Hsu
Newsletter #003: Anthropic Reasoning — Anthropic Bias by Nick Bostrom; SIA > SSA by Joe Carlsmith; reincarnation from Michael Huemer; immortal sleeping beauty from Jens Jäger
Thanks for this information. It helps bring me up to date on a subject I have long thought about.
When I first read Lawrence Wright's book _Twins_ many years ago, I was astonished. Obviously, the undeniable likeness of adopted twins raised apart was mind-blowing, but what really got me was that the twins raised apart and unaware of each others' existence actually grew MORE SIMILAR as they got older.
And yet the media, and even academia, and the public seem to still believe that we are mostly blank slates, and products or our environment, and government programs can correct all societal problems. Why is that, I wonder.
(BTW I recommend political science professor John Hibbing's 2013 book about the inheritance of the Left-Right political difference book _Predisposed: Liberals, Conservatives, and the Biology of Political Differences_)