the nature and nurture of generosity: what can we learn from behavioral genetics? rené bekkers...

The Nature and Nurture of Generosity:

What can we learn from behavioral genetics?

René BekkersCenter for Philanthropic Studies

VU University Amsterdam

WIMPS, November 18, 2014

WIMPS, IUPUI 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, 2014

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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, 2014

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Prosocial behavior

Formal: philanthro

py

Money Time

Informal: helping

Social suppo

rtCare

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Number of publications per year about philanthropy by academic discipline (1899-2009)

1899-1970

1970-1975

1976-1980

1981-1985

1986-1989

1991-1994

1995-1999

2000-2005

0

50

100

150

200

250other

natural sciences

education and health

public admin-istration

marketing & communication

philanthropic studies

economics

sociology

psychology

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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.com

http://www.understandingphilanthropy.com/

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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

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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?

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Selection and causation

Education Behavior

IQ,Other factors

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All selection, no causation

Education Behavior

IQ,Other factors


Selection and Causation

Education

Factors X 1…n

Participation

About 60%?

IQ, parental income, social science classes,

college plans, extraversion, openness to

experienceBekkers, 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.


Selection, causation, mediation

Mediating variable

Education Behavior

IQ, other factors

Another mediating variable


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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.

November 18, 2014


The ideal experiment would randomize education

VWO = higher secondary education (≤ gymnasium)VMBO = lower vocational education

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Monozygotic twins

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The unique environmental influence of education

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Note that shared environmental influences are also excluded by design in this analysis

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What behavioral geneticists do: the ACE model

A Additive genetic effects

Typically 40-60%

C Common (shared) environmental effects

Typically less than 10% (often zero)

E Unique (non-shared) environmental effects (including error)

Typically 30-50%

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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:

“Heritability describes what is; it does not predict what could be”November 18, 2014

http://www.theatlantic.com/education/archive/2014/11/is-being-good-at-science-a-genetic-trait/382287/2/



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ACE mediated effects model

A Religiousness

C Prosocial behavior

E

November 18, 2014

Koenig et al., 2007; n= 165 MZ and 100 DZ twin pairs

A C E

Total effect on prosocial behavior

10.2 27.6 62.3

Mediated by religiousness 7.5 (73.5

%)

13.6(49.3

%)

2.9(4.7%

)

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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).

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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.

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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.

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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, 2014

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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.

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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.

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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).

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Environment mediation model

Religiousness

E Prosocial behavior

Education

November 18, 2014

Note that this is a unique environment mediation model

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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.

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33

Assessing zygosity

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Are twins different at all?

Education Religious affiliation

MZ 55% 50%

DZ 64% 53%

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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:

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ACE model results

A C EEducation 29.8 38.6 31.5

Strength of religiosity 22.8 32.7 39.3

Frequency of church attendance 46.7 53.3

Amount donated ($) 33.7 66.3

Hours volunteered 15.8 84.2

Financial assistance to friends / family

17.7 82.3

Hours helping friends / family 26.6 73.5

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ACE model for volunteer hours

84.2

ACE

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84.2

ACE

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84.2

ACE

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15.8

ACE

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15.8

ACE

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15.8

ACE

November 18, 2014

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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, 2014

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The higher educated give more

November 18, 2014

These differences are massive: amounts donated in the top category are nine times the amount donated in the lowest

category

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The higher educated volunteer more

November 18, 2014

Again, large differences

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Informal prosocial behaviors

November 18, 2014

Perhaps Americans with less education know more people in need of support?

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The religious give more

November 18, 2014

Religious giving is included in this figure. Excluding donations to religion, the differences

are much smaller.

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The religious volunteer more

November 18, 2014

This figure includes volunteering for religious organizations.

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Informal prosocial behaviors

November 18, 2014

Perhaps Americans who attend church less often know more people in need of financial assistance and support?

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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, 2014

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Educational gradients among MZ twins

November 18, 2014

high school or less some college more than some college

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

Giving Non-religious givingVolunteering Non-religious volunteering

Z-s

tandard

ized v

alu

es

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Giving by co-twin

November 18, 2014

1 2 3 1 2 3 1 2 3

1. high school or less

2. some college 3. more than some college

-0.30

-0.10

0.10

0.30

MZDZ

Co-twin educationx R education

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Education and giving

Between siblings, DZ twins, and MZ

twins

FE DZ twins FE MZ twins0

50

100

150

200

250

300

350

400***

*** p <.001

***

November 18, 2014

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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, 2014

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Education and giving among MZs

Between Within Reduced within

Mediated reduced within

0

20

40

60

80

100

120

140

160

180

Total amount donatedexcluding religion

***

***

*** p <.001

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Education estimates on total giving



0

50

100

150

200

250

+1SE

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Education and volunteering



-10

-8

-6

-4

-2

0

2

4

6

8

10

hours volunteeredexcluding religious

November 18, 2014

***

***

*** p <.001

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Resources and volunteering

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*** p <.001

Between Sibs

Between Sibs

Between Sibs

Between Sibs

Between Sibs

-50

0

50

100

150

200

CollegeWages *$100Assets *$1k

*

*

**

*

**

*** p <.01

* p <.05

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November 18, 2014

*** p <.001

Between MZ

Between MZ

Between MZ

Between MZ

Between MZ

-50

0

50

100

150

200


******

***

**

******

*** p <.01

* p <.05

WIMPS, IUPUI 59


November 18, 2014

*** p <.001

Between MZ

Between MZ

Between MZ

Between MZ

Between MZ

-40

-20

0

20

40

60

80

100


*

****

***

***

** p <.01

* p <.05

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November 18, 2014

*** p <.001

Fixed MZ

Fixed MZ

Fixed MZ

Fixed MZ

Fixed MZ

-40

-20

0

20

40

60

80

100


** p <.01

* p <.05

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Church attendance and giving



0

5

10

15

20

25

Amountexcluding religion

*** p <.001

November 18, 2014

***

****** ***

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Church attendance and volunteering



-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1


November 18, 2014

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Strength of religiosity and giving



-100

-50

0

50

100

150

200

250

300

350

Amountexcluding religion

November 18, 2014

*

*

*

* p <.05

WIMPS, IUPUI 64

Religiosity and volunteering



0

5

10

15

20

25

30

35

40


November 18, 2014

**

**

***

***

******

***

*** p <.001; ** p < .01

65November 18, 2014 WIMPS, IUPUI

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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.

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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, 2014

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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, 2014

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…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.

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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).

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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, 2014

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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, 2014

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Schooling effects on income

Between Siblings FE

DZ FE MZ FE-5

0

5

10

15

20

25

30

35

Education (12 cat)College+

***

***

*** p <.001

***

***

***

***

November 18, 2014

René BekkersCenter for Philanthropic Studies

VU University [email protected]

Blog: http://renebekkers.wordpress.com

Twitter: @renebekkers

mailto:[email protected]



http://renebekkers.wordpress.com/

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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, 2014

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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.

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MeasuresDonations. 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.

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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, 2014

the nature and nurture of generosity: what can we learn from behavioral genetics? rené bekkers...

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