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Biology & Philosophy

, Volume 25, Issue 1, pp 1–31 | Cite as

Three puzzles and eight gaps: what heritability studies and critical commentaries have not paid enough attention to

  • Peter TaylorEmail author
Article

Abstract

This article examines eight “gaps” in order to clarify why the quantitative genetics methods of partitioning variation of a trait into heritability and other components has very limited power to show anything clear and useful about genetic and environmental influences, especially for human behaviors and other traits. The first two gaps should be kept open; the others should be bridged or the difficulty of doing so should be acknowledged: 1. Key terms have multiple meanings that are distinct; 2. Statistical patterns are distinct from measurable underlying factors; 3. Translation from statistical analyses to hypotheses about measurable factors is difficult; 4. Predictions based on extrapolations from existing patterns of variation may not match outcomes; 5. The partitioning of variation in human studies does not reliably estimate the intended quantities; 6. Translation from statistical analyses to hypotheses about the measurable factors is even more difficult in light of the possible heterogeneity of underlying genetic or environmental factors; 7. Many steps lie between the analysis of observed traits and interventions based on well-founded claims about the causal influence of genetic or environmental factors; 8. Explanation of variation within groups does not translate to explanation of differences among groups. At the start, I engage readers’ attention with three puzzles that have not been resolved by past debates. The puzzles concern generational increases in IQ test scores, the possibility of underlying heterogeneity, and the translation of methods from selective breeding into human genetics. After discussing the gaps, I present each puzzle in a new light and point to several new puzzles that invite attention from analysts of variation in quantitative genetics and in social science more generally. The article’s critical perspectives on agricultural, laboratory, and human heritability studies are intended to elicit further contributions from readers across the fields of history, philosophy, sociology, and politics of biology and in the sciences.

Keywords

Data analysis Environmental Genetic Group differences Heritability Heterogeneity IQ paradox Measurable factors Quantitative genetics Selective breeding Twin studies 

Notes

Acknowledgments

This article is based on research supported by the National Science Foundation under grant SES–0634744. The comments of Hamish Spencer and anonymous reviewers of this manuscript and a related one helped in the revision process.

References

  1. Byth DE, Eisemann RL, DeLacy IH (1976) Two-way pattern analysis of a large data set to evaluate genotypic adaptation. Heredity 37(2):215–230CrossRefGoogle Scholar
  2. Davey-Smith G, Ebrahim S (2007) Mendelian randomization: genetic variants as instruments for strengthening causal influences in observational studies. In: Weinstein M, Vaupel JW, Wachter KW (eds) Biosocial surveys. National Academies Press, Washington DC, pp 336–366Google Scholar
  3. Dickens WT, Flynn JR (2001) Heritability estimates versus large environmental effects: the IQ paradox resolved. Psychol Rev 108(2):346–369CrossRefGoogle Scholar
  4. Downes SM (2004) Heredity and heritability. In: Zalta EN (ed) The stanford encyclopedia of philosophy. (http://plato.stanford.edu/entries/heredity/ (viewed 11 May 2006)
  5. Falconer DS, Mackay TFC (1996) Introduction to quantitative genetics, 4th edn. Longman, HarlowGoogle Scholar
  6. Flynn JR (1994) IQ gains over time. In: Sternberg RJ (ed) Encyclopedia of human intelligence. Macmillan, New York, pp 617–623Google Scholar
  7. Flynn JR (2000) How to defend humane ideals: substitutes for objectivity. University of Nebraska Press, Lincoln, NEGoogle Scholar
  8. Freedman DA (2005) Linear statistical models for causation: a critical review. In: Everitt B, Howell D (eds) Encyclopedia of statistics in the behavioral sciences. Wiley, ChichesterGoogle Scholar
  9. Fryer R, Levitt S (2004) Understanding the black-white test score gap in the first two years of school. Rev Econ Stat 86(2):447–464CrossRefGoogle Scholar
  10. Gelman A, Hill J (2007) Data analysis using regression and multilevel/hierarchical models. Cambridge University Press, New YorkGoogle Scholar
  11. Jacquard A (1983) Heritability: one word, three concepts. Biometrics 39:465–477CrossRefGoogle Scholar
  12. Jencks C, Phillips M (eds) (1998) The black-white test score gap. Brookings Institution Press, Washington, DCGoogle Scholar
  13. Jensen AR (1969) How much can we boost IQ and scholastic achievement? Harv Educ Rev 39:1–123Google Scholar
  14. Jensen AR (1970) Race and the genetics of intelligence: a reply to Lewontin. Bull At Sci 26:17–23Google Scholar
  15. Kaplan JM (2000) The limits and lies of human genetic research. Routledge, New YorkGoogle Scholar
  16. Kendler KS (2005) Reply to J. Joseph, research paradigms of psychiatric genetics. Am J Psychiatry 162:1985–1986CrossRefGoogle Scholar
  17. Kendler KS, Prescott CA (2006) Genes, environment, and psychopathology: understanding the causes of psychiatric and substance abuse disorders. The Guilford Press, New YorkGoogle Scholar
  18. Khoury MJ, Little J, Gwinn M, Ioannidis JP (2007) On the synthesis and interpretation of consistent but weak gene-disease associations in the era of genome-wide association studies. Int J Epidemiol 36:439–445CrossRefGoogle Scholar
  19. Lewontin RC (1970a) Race and intelligence. Bull At Sci 26:2–8Google Scholar
  20. Lewontin RC (1970b) Further remarks on race and the genetics of intelligence. Bull At Sci 26:23–25Google Scholar
  21. Lewontin RC (1974) The analysis of variance and the analysis of causes. Am J Hum Genet 26:400–411Google Scholar
  22. Lindman HR (1992) Analysis of variance in experimental design. Springer, New YorkGoogle Scholar
  23. Lynch M, Walsh B (1998) Genetics and analysis of quantitative traits. Sinauer, SunderlandGoogle Scholar
  24. Majumder PP, Ghosh S (2005) Mapping quantitative trait loci in humans: achievements and limitations. J Clin Investig 115(6):1419–1424CrossRefGoogle Scholar
  25. McLaughlin P (1998) Rethinking the agrarian question: the limits of essentialism and the promise of evolutionism. Hum Ecol Rev 5:25–39Google Scholar
  26. Miele F (2002) Intelligence, race, and genetics: conversations with Arthur Jensen. Westview Press, BoulderGoogle Scholar
  27. Moffitt TE, Caspi A, Rutter M (2005) Strategy for investigating interactions between measured genes and measured environments. Arch Gen Psychiatry 62(5):473–481CrossRefGoogle Scholar
  28. Neisser U, Boodoo G, Bouchard TJ, Boykin AW, Brody N, Ceci SJ, Halpern DF, Loehlin JC, Perloff R, Sternberg RJ, Urbina S (1996) Intelligence: knowns and unknowns. Am Psychol 51:77–101CrossRefGoogle Scholar
  29. Nisbett RE (1998) Race, genetics, and IQ. In: Jencks C, Phillips M (eds) The black-white test score gap. Brookings Institution Press, Washington, DC, pp 86–102Google Scholar
  30. Nuffield Council on Bioethics (2002) Genetics and human behavior: the ethical context. http://www.nuffieldbioethics.org (viewed 22 Jun. 2007)
  31. Otto SP, Christiansen FB, Feldman MW (1995) Genetic and cultural inheritance of continuous traits. Stanford University Morrison Institute for Population and Resource Studies Working Paper Series No. 64. http://www.stanford.edu/group/morrinst/pdf/64.pdf (viewed 24 March 2009)
  32. Parens E (2004) Genetic differences and human identities: on why talking about behavioral genetics is important and difficult, Hastings center report (January-February). pp S1–S36Google Scholar
  33. Plomin R, Asbury K (2006) Nature and nurture: genetic and environmental influences on behavior. Ann Am Acad Political Soc Sci 600(1):86–98CrossRefGoogle Scholar
  34. Plomin R, DeFries JC, Loehlin JC (1977) Genotype-environment interaction correlation in analysis of human behavior. Psychol Bull 84:309–322CrossRefGoogle Scholar
  35. Richardson K, Norgate S (2005) The equal environments assumption of classical twin studies may not hold. Br J Educ Psychol 75(3):339–350CrossRefGoogle Scholar
  36. Rutter M (2002) Nature, nurture, and development: from evangelism through science toward policy and practice. Child Dev 73(1):1–21CrossRefGoogle Scholar
  37. Sesardic N (2005) Making sense of heritability. Cambridge University Press, CambridgeCrossRefGoogle Scholar
  38. Taylor PJ (2005) Unruly complexity: ecology, interpretation, engagement. University of Chicago Press, ChicagoGoogle Scholar
  39. Taylor PJ (2006a) Heritability and heterogeneity: on the limited relevance of heritability in investigating genetic and environmental factors. Biol Theory Integr Dev Evol Cognit 1(2):150–164Google Scholar
  40. Taylor PJ (2006b) Heritability and heterogeneity: on the irrelevance of heritability in explaining differences between means for different human groups or generations. Biol Theory Integr Dev Evol Cognit 1(4):392–401Google Scholar
  41. Taylor PJ (2007) The unreliability of high human heritability estimates and small shared effects of growing up in the same family. Biol Theory Integr Dev Evol Cognit 2(4):387–397Google Scholar
  42. Taylor PJ (2008a) Puzzles in the history and philosophy of heredity that warrant more attention. http://sicw.wikispaces.com/HeredityVariationPuzzles (viewed 12 Aug. 2008)
  43. Taylor PJ (2008b) The under-recognized implications of heterogeneity: opportunities for fresh views on scientific, philosophical, and social debates about heritability. Hist Philos Life Sci 30:423–448Google Scholar
  44. Taylor PJ (2009) Critical assumptions of classical quantitative genetics and twin studies that warrant more attention (manuscript)Google Scholar
  45. Turkheimer E (2000) Three laws of behavior genetics and what they mean. Curr Dir in Psychol Sci 9(5):160–164CrossRefGoogle Scholar
  46. Turkheimer E, Haley A, Waldron M, D’Onofrio B, Gottesman II (2003) Socioeconomic status modifies heritability of IQ in young children. Psychol Sci 16(6):623–628CrossRefGoogle Scholar
  47. Wikipedia (2008) Heritability. http://en.wikipedia.org/wiki/Heritability (viewed 14 Mar 2008)

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.Programs in Science, Technology & Values and Critical & Creative ThinkingUniversity of MassachusettsBostonUSA

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