Behavior genetics and the “HORB” argument
Here I outline a type of argument often used by critics of behavior genetics, which I dub the “Heritability Of Random Bullshit”, or “HORB”, argument. This argument amounts to pointing out that many human behaviors are reported by behavior genetic studies (typically those involving twins) to be partly heritable (i.e. genetically influenced), even ones that seem ridiculously culturally-specific. The associated belief that all sorts of human behaviors are partly genetic is often cited as ridiculous, and thus as a reason that human behavior genetic research is on highly shaky ground, to say the least. Here are some examples of the HORB argument being used (references removed if the formatting looked ugly when I copied and pasted the article text here):
“Heritability estimates are compiled for everything from sexual orientation to political tendency and ‘compulsive shopping’.” (Rose 2006)
“Readers have been informed … that the heritability of controllable life events is 53% among women and 14% among men, while the heritability of uncontrollable life events is 22% among women and zero among men.” (Kamin & Goldberger 2002)
“…many behavioral scientists, psychologists especially, continue to believe that behavior genetics provides evidence for the inheritance of behaviors such as intelligence, parenting, morality, and even television viewing!” (Greenberg 2011)
“Apparently, whatever “phenotype” a twin study claims to be genetically heritable simply is genetically heritable (to think otherwise would be to doubt the methodology). This includes such things as voting behavior (Fowler et al. 2008); credit card debt (De Neve & Fowler 2010); mobile phone use (including amount of time spent texting) (Miller et al. 2012); and consumer preferences for soups and snacks, hybrid cars, science fiction movies, and jazz (Simonson & Sela 2011).” (Charney 2012)
“These new datasets opened up tremendous scientific opportunities for behavior geneticists. One part of this was the huge range of behaviors on which they could publish — from cognitive abilities, personality traits, and psychopathologies all the way to curiosities like television watching habits, political viewpoints, and beverages consumed.” (Panofsky 2014)
“Studies of twins and adopted children have claimed substantial heritability of everything from time spent watching television to religious conservatism and what brand of beer you prefer.” (Wahlsten 1994)
“…many psychologists continue to act as if behavioral genetics provides evidence for the inheritance of behaviors as varied as intelligence (Jensen, 1969), parenting (Scarr, 1992), morality (Wilson, 1975), temperament (Buss & Plomin, 1984), television viewing (Plomin, Corley, DeFries, & Fulker, 1990), and even the role in human development of the “environment” (Plomin, 1986; Plomin & Daniels, 1987)!” (Lerner 1995)
The common thread underlying all the above examples of the HORB argument is that it is ridiculous to imagine that all sorts of human behaviors — be they TV watching, morality, cell phone use, parenting, what kind of soup you like, or whatever — could be “genetic” in any reasonable sense of the word. But clearly this is not necessarily true, at least if behavior geneticists are to be believed. As Fowler & Dawes write, “Genes playing a role in important hormonal systems that regulate social behavior are likely to influence a wide variety of outcomes, a phenomenon known as “pleiotropy”” (Fowler & Dawes 2013). Thus, the causal path being proposed appears to be genes -> hormonal systems -> all sorts of different types of social behavior. So this is supposedly an indirect genetic effect, assuming a whole bunch of things, e.g. that hormonal systems are regulated entirely by genes.
But there are other examples of behavior geneticists actively embracing the HORB argument. The most famous example is undoubtedly Turkheimer’s “first law of behavior genetics” — that “all human behavioral traits are heritable”. (Turkheimer 2000) Elsewhere, Turkheimer and his colleagues wrote:
“Once we accept that basically everything — not only schizophrenia and intelligence, but also marital status and television watching — is heritable, it becomes clear that specific estimates of heritability are not very important.” (Johnson et al. 2009)
Here are some other instances of this argument, which is typically portrayed as a reason against the validity of behavior genetics and twin studies, being used by people trying to defend these very methodologies.
“More whimsically, twin studies have suggested a major role for genes in traits as diverse as television watching, social attitudes, divorce and, at the sublime end of human existence, happiness itself!” (Martin et al. 1997)
“…with all the usual subjects exhausted, and many dissertations left to write, people conducted twin studies of less likely candidates, and to a troubling degree these all came out to be heritable as well. How much television children watch is heritable. Political attitudes are heritable. Divorce is heritable. There has been no end to it, especially as twin studies have expanded into the yet-to-be exhausted areas of economics (risk preference) and political science (voting).” (Turkheimer 2011)
“To a first approximation, every reliably measured behavioral trait shows positive heritability — even constructs such as television viewing (Plomin et al. 1990) and political attitudes (Eaves et al. 1999). Any arbitrary “disorder” composed of unrelated but heritable symptoms will show credible heritability.” (Keller & Miller 2006)
