1. The Nature and Nurture of Generosity: What can we learn from behavioral genetics? René Bekkers Center for Philanthropic Studies VU University Amsterdam WIMPS, November 18, 2014

2. Thanks To the McArthur Foundation for funding the MIDUS data collection. Colleagues who gave feedback: Dorret Boomsma, Dinand Webbink, Sara Konrath, Paul van Lange, Daniëlle Posthuma. To be submitted as a chapter for a CESifo volume published at MIT Press. November 18, 2014WIMPS, IUPUI2

3. November 18, 2014WIMPS, IUPUI3

4. November 18, 2014WIMPS, IUPUI4

5. November 18, 2014WIMPS, IUPUI5

6. Three questions How alike are twins in the United States with respect to prosocial behavior? Are differences among twins in giving and volunteering related to differences in education and religion? If so, what explains these relationships? November 18, 2014WIMPS, IUPUI6

7. Prosocial behavior Formal: philanthropy MoneyTime Informal: helping Social support Care WIMPS, IUPUINovember 18, 20147

8. Number of publications per year about philanthropy by academic discipline (1899-2009) WIMPS, IUPUINovember 18, 20148 Source: Bekkers & Dursun (2013), based on Bekkers & Wiepking (2011). ‘A Literature Review of Empirical Studies of Philanthropy: Eight Mechanisms that Drive Charitable Giving’. Nonprofit and Voluntary Sector Quarterly, 40(5): 924-973. Available at www.understandingphilanthropy.comwww.understandingphilanthropy.com

9. Ubiquitous correlates of philanthropy 1.Religion: – Affiliation (yes>no) – Denomination (Protestant>Catholic) – Participation (church attendance) 2.Education: – Level achieved The variance between fields of study is small WIMPS, IUPUINovember 18, 20149

10. Where do the correlations originate? The more general research questions: 1.Why are religion and education correlated with prosocial behavior? 2.To what extent are these relationships the result of environmental influences? 3.Are these relationships causal? November 18, 2014WIMPS, IUPUI10

11. Selection and causation EducationBehavior IQ, Other factors November 18, 2014WIMPS, IUPUI11

12. All selection, no causation EducationBehavior IQ, Other factors November 18, 2014WIMPS, IUPUI12

13. Selection and Causation Education Factors X 1…n Participation About 60%? IQ, parental income, social science classes, college plans, extraversion, openness to experience Bekkers, R. & Ruiter, S. (2008). ‘Education and voluntary association participation: Evidence for selection and causation’. Paper presented at the 103d ASA Annual Meeting, Boston, August 2, 2008. November 18, 2014WIMPS, IUPUI13

14. Selection, causation, mediation Mediating variable EducationBehavior IQ, other factors Another mediating variable November 18, 2014WIMPS, IUPUI14

15. November 18, 2014WIMPS, IUPUI15

16. Three ‘theories’ on philanthropy Philanthropy varies between social groups 1.because the resources of group members vary; 2.because the social values of groups vary; 3.because members of different groups have different self-identities. WIMPS, IUPUINovember 18, 201416

17. November 18, 2014WIMPS, IUPUI17

18. WIMPS, IUPUINovember 18, 2014 The ideal experiment would randomize education VWO = higher secondary education (≤ gymnasium) VMBO = lower vocational education 18

19. Monozygotic twins WIMPS, IUPUINovember 18, 201419

20. The unique environmental influence of education WIMPS, IUPUINovember 18, 201420 Note that shared environmental influences are also excluded by design in this analysis

21. What behavioral geneticists do: the ACE model AAdditive genetic effectsTypically 40-60% CCommon (shared) environmental effects Typically less than 10% (often zero) EUnique (non-shared) environmental effects (including error) Typically 30-50% November 18, 2014WIMPS, IUPUI21

22. Note The first law of behavior genetics, as formulated by Eric Turkheimer (2000): “All human behavioral traits are heritable” Eva Krapohl in a recent interview in The Atlantic:interview in The Atlantic “Heritability describes what is; it does not predict what could be” November 18, 2014WIMPS, IUPUI22

23. ACE mediated effects model AReligiousness CProsocial behavior E November 18, 2014WIMPS, IUPUI Koenig et al., 2007; n= 165 MZ and 100 DZ twin pairs ACE Total effect on prosocial behavior10.227.662.3 Mediated by religiousness7.5 (73.5%) 13.6 (49.3%) 2.9 (4.7%) 23

24. Biometric model fitting Fit statistics of various biometric models are compared to identify the best-fitting model. Models depend on assumptions such as the Equal Environments Assumption. The EEA is often disputed theoretically. Empirical tests show it is often violated. The resulting bias, however, seems to be minor (see Felson, Soc.Sc.Res., 2014). November 18, 2014WIMPS, IUPUI24

25. What molecular geneticists do Genome Wide Association Studies (GWAS): identify ‘candidate genes’ that could explain variance in some outcome variable. Typically, individual genes like OXTR and DRD4 explain tiny fractions of variance (<1%). Typically, all single nucleotide polymorphisms (SNPs) combined explain less variance (16% of education) than estimated in biometric models (35%) – ‘missing heritability’ problem. November 18, 2014WIMPS, IUPUI25

26. Where is the social science? In the variance explained by shared and unique environmental factors. Let us rule out genetic effects by looking at monozygotic twins only. Any difference between MZ twins must have roots in the unique environment. This choice avoids problems with the EEA. Note that MZ twins also share 100% of shared environmental effects. November 18, 2014WIMPS, IUPUI26

27. The problem “…families whose unobservable characteristics cause them to have a high likelihood of volunteering are also more likely to educate their children, so the relationship between schooling and volunteering is just a correlation caused by an excluded common cause.” John Gibson (2001) November 18, 2014WIMPS, IUPUI27

28. This is not my idea In 2001, New Zealand economist John Gibson published a study of volunteering among 85 identical twin pairs. Though education in the pooled sample is associated with more volunteering, pairwise comparisons reveal the opposite. The twin with more years of education was found to volunteer fewer hours. November 18, 2014WIMPS, IUPUI28

29. The implication Genetic effects cause a positive association between education and volunteering. Unique environmental effects of education on volunteering are negative in this sample. One interpretation of the negative effect is that it is the result of the opportunity cost of volunteering, potentially amplified by a decision making process within the household. November 18, 2014WIMPS, IUPUI29

30. Related literature The twin fixed effects model has been used in economics to estimate the influence of schooling on income since the 1970s (Behrman & Taubman, 1976; Ashenfelter & Kreuger, 1994; Ashenfelter & Rouse, 1998; Isacsson, 1999; Miller, Mulvey & Martin, 1995; Bonjour et al., 2003). November 18, 2014WIMPS, IUPUI30

31. Environment mediation model Religiousness EProsocial behavior Education November 18, 2014WIMPS, IUPUI31 Note that this is a unique environment mediation model

32. The MIDUS data Two wave longitudinal panel survey on Midlife in the United States (1995 and 2005) sponsored by the McArthur Foundation. The RDD sample selection procedure included twin screening questions. Only English-speaking respondents aged 25-74 living in the US who were physically and mentally able to complete the interview were allowed to participate. November 18, 2014WIMPS, IUPUI32

33. Assessing zygosity November 18, 2014WIMPS, IUPUI33

34. Are twins different at all? EducationReligious affiliation MZ55%50% DZ64%53% November 18, 2014WIMPS, IUPUI Proportions of respondents from the same twin pair not reporting exactly the same level of education and religious affiliation Yes – here’s the discordance table: 34

35. ACE model results ACE Education29.838.631.5 Strength of religiosity22.832.739.3 Frequency of church attendance46.753.3 Amount donated ($)33.766.3 Hours volunteered15.884.2 Financial assistance to friends / family17.782.3 Hours helping friends / family26.673.5 November 18, 2014WIMPS, IUPUI35

36. ACE model for volunteer hours November 18, 2014WIMPS, IUPUI36

37. ACE model for volunteer hours November 18, 2014WIMPS, IUPUI37

38. ACE model for volunteer hours November 18, 2014WIMPS, IUPUI38

39. ACE model for volunteer hours November 18, 2014WIMPS, IUPUI39

40. ACE model for volunteer hours November 18, 2014WIMPS, IUPUI40

41. ACE model for volunteer hours November 18, 2014WIMPS, IUPUI41

42. Remember “Heritability describes what is; it does not predict what could be”. These are the results of educational careers and systems for those in midlife in the US. “All human behavioral traits are heritable”. 25% is not much compared to 75% for IQ. November 18, 2014WIMPS, IUPUI42

43. The higher educated give more November 18, 2014WIMPS, IUPUI43 These differences are massive: amounts donated in the top category are nine times the amount donated in the lowest category

44. The higher educated volunteer more November 18, 2014WIMPS, IUPUI44 Again, large differences

45. Informal prosocial behaviors November 18, 2014WIMPS, IUPUI45 Perhaps Americans with less education know more people in need of support?

46. The religious give more November 18, 2014WIMPS, IUPUI46 Religious giving is included in this figure. Excluding donations to religion, the differences are much smaller.

47. The religious volunteer more November 18, 2014WIMPS, IUPUI47 This figure includes volunteering for religious organizations.

48. Informal prosocial behaviors November 18, 2014WIMPS, IUPUI48 Perhaps Americans who attend church less often know more people in need of financial assistance and support?

49. Two basic regression models 1.Between effects model: ignores the twin pair structure, replicates bivariate analyses. Includes genetic + environmental effects. 2.Within MZ twin fixed effects model: does the higher educated / more religious twin of an MZ pair give and volunteer more than the less educated / religious co-twin? Includes environmental effects only. November 18, 2014WIMPS, IUPUI49

50. Educational gradients among MZ twins November 18, 2014WIMPS, IUPUI50

51. Giving by co-twin November 18, 2014WIMPS, IUPUI51

52. Education and giving November 18, 2014WIMPS, IUPUI52

53. Two further models Reduced form within MZ twin model: excludes religious denomination dummies, retaining education, church attendance and strength of religiosity. Mediated reduced form within MZ twin model: adds social responsibility, prosocial self-identity, household income, and assets. November 18, 2014WIMPS, IUPUI53

54. Education and giving among MZs November 18, 2014WIMPS, IUPUI54

55. Education estimates on total giving November 18, 2014WIMPS, IUPUI55

56. Education and volunteering November 18, 2014WIMPS, IUPUI *** *** p <.001 56

57. Resources and volunteering November 18, 2014WIMPS, IUPUI *** p <.001 57 * * ** * * ** p <.01 * p <.05

58. Resources and volunteering November 18, 2014WIMPS, IUPUI *** p <.001 58 *** ** *** * ** p <.01 * p <.05

59. Resources and volunteering November 18, 2014WIMPS, IUPUI *** p <.001 59 * * *** ** p <.01 * p <.05

60. Resources and volunteering November 18, 2014WIMPS, IUPUI *** p <.001 60 ** p <.01 * p <.05

61. Church attendance and giving November 18, 2014WIMPS, IUPUI *** 61

62. Church attendance and volunteering November 18, 2014WIMPS, IUPUI62

63. Strength of religiosity and giving November 18, 2014WIMPS, IUPUI * * * * p <.05 63

64. Religiosity and volunteering November 18, 2014WIMPS, IUPUI ** *** *** p <.001; ** p <.01 64

65. November 18, 2014WIMPS, IUPUI65

66. November 18, 2014WIMPS, IUPUI66

67. Conclusions The association between the level of education and giving and volunteering is due to genetic or shared environmental effects. The association between religiosity and charitable giving is due to unique environmental effects, but it is limited to church contributions. Religiosity nurtures volunteering, also beyond religious organizations. November 18, 2014WIMPS, IUPUI67

68. Mediation Education hardly mediates unique environmental influences on giving (-0.5%) or volunteering (1.8%). Religion mediates unique environmental influences on giving (15.6%) but not on volunteering (2.0%). Education effects are partly mediated (25%) by income and assets. Religiosity effects are mediated by prosocial self-identity (55%), but not by prosocial values. November 18, 2014WIMPS, IUPUI68

69. Or vice versa Perhaps volunteering nurtures religiosity. Or perhaps an omitted (shared?) environmental effect nurtures volunteering and religiosity. We cannot infer causality from the twin fixed effects model. But we can look at changes in religiosity and volunteering between the two waves. November 18, 2014WIMPS, IUPUI69

70. …and? Respondents who quit volunteering between the first and the second wave are less frequently attending church and report lower strength of religiosity in the second wave than in the first wave. Respondents who started volunteering are more frequently attending church in the second wave. November 18, 2014WIMPS, IUPUI70

71. The measurement error problem Could differential measurement error explain the pattern of results? That is unlikely. The test-retest correlation of education is higher (.87) than that of the frequency of church attendance (.72). It is similar to strength of religiosity (.84). November 18, 2014WIMPS, IUPUI71

72. The variance problem Could a differential lack of variance explain the pattern of results? That is unlikely. MZ twins are more likely to be discordant with respect to education (55%) than with respect to religion (50%). November 18, 2014WIMPS, IUPUI72

73. Future directions Replicate this finding using data from other samples of twins, in the US and beyond. Examine other dependent variables using this method: trust, subjective well being, prosocial values... November 18, 2014WIMPS, IUPUI73

74. Schooling effects on income November 18, 2014WIMPS, IUPUI74

75. René Bekkers Center for Philanthropic Studies VU University Amsterdam r.bekkers@vu.nl Blog: http://renebekkers.wordpress.comhttp://renebekkers.wordpress.com Twitter: @renebekkers

76. References Bekkers, R. & Dursun, E. (2013). “A Brief History of Research on Philanthropy.” http://www.understandingphilanthropy.com Felson, J. (2014). “What can we learn from twin studies? A comprehensive evaluation of the equal environments assumption.” Social Science Research, 43: 184-199. Gibson, J. (2001). “Unobservable Family Effects and the Apparent External Benefits of Education.” Economics of Education Review, 20: 225-233. Koenig, L.B., McGue, M., Krueger, R.F., Bouchard, T.J. (2007). “Religiousness, Antisocial Behavior, and Altruism: Genetic and Environmental Mediation.” Journal of Personality, 75: 265-290. Reuter, M., Felten, A., Penz, S., Mainzer, A., Markett, S. & Montag, C. (2013). “The influence of dopaminergic gene variants on decision making in the ultimatum game.” Frontiers in Human Neuroscience, 7: 1-8. November 18, 2014WIMPS, IUPUI76

77. More references Ashenfelter, O., & Krueger, A. (1994). “Estimates of the economic return to schooling from a new sample of twins.” American Economic Review, 84, 1157–1173. Ashenfelter, O., & Rouse, C. (1998). “Income, schooling and ability: Evidence from a new sample of identical twins.” Quarterly Journal of Economics, 113, 153–284. Behrman, J. & Taubman, P. (1976). “Intergenerational Transmission of Income and Wealth.” American Economic Review, 66: 436-440. Behrman, J. & Rosenzweig, M.R. (1999). “Ability biases in schooling returns and twins: a test and new estimates.” Economics of Education Review, 18: 159-167. Bonjour, D., Cherkas, L., Haskel, J., Hawkes, D., & Spector, T. (2003). “Returns to Education: Evidence from UK Twins.” American Economic Review, 93: 1799-1812. Isacsson, G. (1999). “Estimates of the Return to Schooling in Sweden from a Large Sample of Twins.” Labour Economics, 6: 471-489. Miller, P., Mulvey, C. & Martin, N. (1995). “What Do Twins Studies Reveal About the Economic Returns to Education? A Comparison of Australian and U.S. Findings." American Economic Review, 85: 586-599. November 18, 2014WIMPS, IUPUI77

78. Measures Donations. Donations to organizations were measured with the following question: “On average, about how many dollars per month do you or your family living with you contribute to each of the following people or organizations? If you contribute food, clothing, or other goods, include their dollar value. (If none, enter "0".)” After this introduction, donations to three categories of organizations were measured: (1) to religious groups; (2) to political organizations or causes; (3) to any other organizations, causes, or charities (including donations made through monthly payroll deductions)? Amounts donated per month were multiplied by 12 to obtain the total amount donated per year. The sum of these contributions is the variable for the total amount donated to organizations. A separate variable was created excluding donations to religion to see if the relationship between religion and philanthropy would also hold for ‘secular giving’. The test-retest correlation of the total amount donated measured in dollars is.25; for the logtransformed amounts the test-retest correlation is.44. For donations to organizations other than religion the test-retest correlation of the dollar amounts is.29; for the log-transformed amounts it is.39. November 18, 2014WIMPS, IUPUI78

79. Volunteering. The questions on volunteering in M1 and M2 asked about four types of formal volunteer work: ‘hospital, nursing home, or other health care-oriented work’, ‘school or other youth-related volunteer work’, ‘volunteer work for political organizations or causes’, and ‘volunteer work for any other organization, cause or charity’. While these questions did not explicitly identify religious organizations, respondents could report volunteering for religious organizations in the question about any ‘other’ organizations. A separate variable was created excluding potentially religious volunteering by computing the sum of hours volunteered in the first three types. The test-retest correlation of the total number of volunteer hours is.38; for the log-transformed hours the test-retest correlation is.46. For the hours volunteered in organizations other than religious organizations the test-retest correlation is.28; for the log-transformed variable it is.36. November 18, 2014WIMPS, IUPUI79

80. November 18, 2014WIMPS, IUPUI80

81. November 18, 2014WIMPS, IUPUI81

82. November 18, 2014WIMPS, IUPUI82

83. November 18, 2014WIMPS, IUPUI83

84. November 18, 2014WIMPS, IUPUI84

85. November 18, 2014WIMPS, IUPUI85