The Fourth Law of Behavior Genetics

Christopher F. Chabris, James J. Lee, David Cesarini, Daniel J. Benjamin, David I. Laibson

    Research output: Contribution to journalArticlepeer-review


    Behavior genetics is the study of the relationship between genetic variation and psychological traits. Turkheimer (2000) proposed “Three Laws of Behavior Genetics” based on empirical regularities observed in studies of twins and other kinships. On the basis of molecular studies that have measured DNA variation directly, we propose a Fourth Law of Behavior Genetics: “A typical human behavioral trait is associated with very many genetic variants, each of which accounts for a very small percentage of the behavioral variability.” This law explains several consistent patterns in the results of gene-discovery studies, including the failure of candidate-gene studies to robustly replicate, the need for genome-wide association studies (and why such studies have a much stronger replication record), and the crucial importance of extremely large samples in these endeavors. We review the evidence in favor of the Fourth Law and discuss its implications for the design and interpretation of gene-behavior research.

    Original languageEnglish (US)
    Pages (from-to)304-312
    Number of pages9
    JournalCurrent Directions in Psychological Science
    Issue number4
    StatePublished - Aug 18 2015


    • behavior genetics
    • genome-wide association studies
    • individual differences
    • molecular genetics
    • polygenic architecture

    ASJC Scopus subject areas

    • General Psychology


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