In their target article, Madole & Harden offer an account of “what it means for genes to be causes” of social outcomes to bolster their claim that genetics should be incorporated into social science with practical implications. Here I object to several key features of their arguments, their representation of the state of science, and claims about the utility of genetics for social science and society.

In this paper I argue that the extent to which a human trait is genetically caused can causally depend upon whether the trait is categorized within human genetics as genetically caused. This makes the kind genetically caused trait an interactive kind. I demonstrate that this thesis is both conceptually coherent and empirically plausible. I outline the core rationale of this thesis and demonstrate its conceptual coherence by drawing upon Waters’ (2007) analysis of genetic causation. I add empirical plausibility to the (...) thesis by describing a hypothetical but empirically plausible mechanism by which the fact that obesity is categorized as genetically caused within human genetics increases the extent to which obesity is in fact genetically caused. (shrink)

The view advanced by Madole & Harden falls back on the dogma of a gene as a DNA sequence that codes for a fixed product with an invariant function regardless of temporal and spatial contexts. This outdated perspective entrenches the metaphor of genes as static units of information and glosses over developmental complexities.

The aim of this virtual special issue is to bring together philosophical and historical perspectives to address long-standing issues in the interpretation, utility, and impacts of quantitative genetics methods and findings. Methodological approaches and the underlying scientific understanding of genetics and heredity have transformed since the field's inception. These advances have brought with them new philosophical issues regarding the interpretation and understanding of quantitative genetic results. The contributions in this issue demonstrate that there is still work to be done integrating (...) old and new methodological and conceptual frameworks. In some cases, new results are interpreted using assumptions based on old concepts and methodologies that need to be explicitly recognised and updated. In other cases, new philosophical tools can be employed to synthesise historical quantitative genetics work with modern methodologies and findings. This introductory article surveys three general themes that have dominated philosophical discussion of quantitative genetics throughout history: (1) how methodologies have changed and transformed our knowledge and interpretations; (2) whether or not quantitative genetics can offer explanations relating to causation and prediction; and (3) the importance of defining the phenotypes under study. We situate the contributions in this virtual special issue within a historical framework addressing these three themes. (shrink)

Heterogeneous treatment effects represent a major issue for medicine as they undermine reliable inference and clinical decision-making. To overcome the issue, the current vision of precision and personalized medicine acknowledges the need to control individual variability in response to treatment. In this paper, we argue that gene-treatment-environment interactions (G × T × E) undermine inferences about individual treatment effects from the results of both genomics-based methodologies—such as genome-wide association studies (GWAS) and genome-wide interaction studies (GWIS)—and randomized controlled trials (RCTs). Then, (...) we argue that N-of-1 trials can be a solution to overcome difficulties in handling individual variability in treatment response. Although this type of trial has been suggested as a promising strategy to assess individual treatment effects, it nonetheless has limitations that limit its use in everyday clinical practice. We analyze the existing variability within the designs of N-of-1 trials in terms of a continuum where each design prioritizes epistemic and pragmatic considerations. We then support wider use of the designs located at the pragmatic end of the explanatory-pragmatic continuum. (shrink)

Research in pharmacogenomics and precision medicine has recently introduced the concept of Polygenic Scores (PGSs), namely, indexes that aggregate the effects that many genetic variants are predicted to have on individual disease risk. The popularity of PGSs is increasing rapidly, but surprisingly little attention has been paid to the idealisations they make about phenotypic development. Indeed, PGSs rely on quantitative genetics models and methods, which involve considerable theoretical assumptions that have been questioned on various grounds. This comes with epistemological and (...) ethical concerns about the use of PGSs in clinical decision-making. In this paper, I investigate to what extent idealisations in genetics models can impact the data gathering and clinical interpretation of genomics findings, particularly the calculation and predictive accuracy of PGSs. Although idealisations are considered ineliminable components of scientific models, they may be legitimate or not depending on the epistemic aims of a model. I thus analyse how various idealisations have been introduced in classical models and progressively readapted throughout the history of genetic theorising. Notably, this process involved important changes in the epistemic purpose of such idealisations, which raises the question of whether they are legitimate in the context of contemporary genomics. (shrink)

The environmental elbow room model of free will posits the unshared proportion of environmental variance in twins is a measure of the degree to which free will may be exercised with respect to one’s life outcomes for a trait. This model attempts to unify the behavioral genetic study of socially important psychological characteristics such as intelligence and academic achievement with Dennett’s broadly compatibilist elbow room notion of free will. We demonstrate that the philosophy and genetics underlying the environmental elbow room (...) model are both fundamentally flawed. Philosophically the degree to which an outcome might be predicted in a given situation does not give any sense of whether the course of action to achieve an outcome was free or unfree. With respect to genetics, quantities such as heritability and its environmental complement, even when they do reflect the actions of independently identifiable causes are not indicative of the chain of decisions one would have to evaluate to judge if an action was freely chosen. We show the contemporary human behavioral genetics focus on heritability is wholly misplaced for purposes of making decisions about policy and free will alike. Variance components sample a single instance of the distribution of variation arising from different sources and do not constrain outcomes in other contexts. The claim that the high heritability of a trait, life outcomes included, makes us less free to change it is similar in key ways to Jensenism’s contention that high heritability makes social change impossible. (shrink)

We received 23 spirited commentaries on our target article from across the disciplines of philosophy, economics, evolutionary genetics, molecular biology, criminology, epidemiology, and law. We organize our reply around three overarching questions: (1) What is a cause? (2) How are randomized controlled trials (RCTs) and within-family genome-wide association studies (GWASs) alike and unalike? (3) Is behavior genetics a qualitatively different enterprise? Throughout our discussion of these questions, we advocate for the idea that behavior genetics shares many of the same pitfalls (...) and promises as environmentally oriented research, medical genetics, and other arenas of the social and behavioral sciences. (shrink)

Madole & Harden argue that just as the results of randomized controlled trials (RCTs) represent gains in causal knowledge and are useful, despite their limitations, so too are the findings of human behavior genetics. We argue that this analogy is misleading. Unlike RCTs, the results of human behavior genetics research cannot suggest efficacious interventions, nor point toward future research.

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). (shrink)