Search Terms Used in the Meta-Analyses

Table S1. Bivariate genetic model fitting estimates for additive genetic (A), shared environment (C), and non- shared environment (E) components of variance in domain specific risk-taking propensity Model AIC χ2 df p Change from full model 2 ∆χ ∆df p Moral risk & Financial risk ACE -1.24 20.76 11 0.04 AE -7.24 20.76 14 0.11 0.00 3 1.00 CE 1.70 29.70 14 0.01 8.93 3 0.03 E 53.85 87.85 17 0.00 67.09 6 0.00 Natural/physical risk & Moral risk ACE 139.10 161.10 11 0.00 AE 136.97 164.97 14 0.00 4.88 3 0.18 CE 142.55 170.55 14 0.00 10.46 3 0.02 E 221.35 245.35 17 0.00 85.25 6 0.00 Cooperation/competition & Moral risk ACE -11.69 10.31 11 0.50 AE -16.61 11.39 14 0.66 1.08 3 0.78 CE -9.83 18.17 14 0.20 7.86 3 0.05 E 34.91 68.91 17 0.00 58.60 6 0.00 Financial risk & Natural/physical risk ACE 14.96 36.96 11 0.00 AE 9.00 37.00 14 0.00 0.04 3 1.00 CE 19.68 47.68 14 0.00 10.72 3 0.01 E 68.69 102.69 17 0.00 65.72 6 0.00 Reproduction & Natural/physical risk ACE 31.50 53.50 11 0.00 AE 25.56 53.56 14 0.00 0.06 3 1.00 CE 36.57 64.57 14 0.00 11.07 3 0.01 E 80.19 114.19 17 0.00 60.68 6 0.00

1 Table S2. Search terms used in the meta-analyses Domains Terms Natural/Physical risk Sensation seeking, novelty seeking, recreational risk, physical risk, extreme sports, bungee Moral risk Moral risk, ethical risk, immoral behavior, dishonesty, crime, antisocial behavior, illegal behavior Financial risk Financial risk, economic risk, portfolio risk, financial portfolio, stock market participation, asset allocation Reproduction Risky sexual behavior, reproductive risk, fertility risk, condom use, sexual risk, unsafe sexual behavior, teenage pregnancy, reproductive age Cooperation/Competition Relational risk, social relationship risk, dictator game, gang, delinquent peers, trust, competition risk, cooperation risk, ultimatum game, prisoner dilemma, social risk, interpersonal risk Safety control Health risk, safety risk, safety, drunk driving, drinking problem, alcohol abuse, precaution, protection, seatbelt use, helmet use, transportation risk Gambling Gamble, gambling

2 Table S3. Summary table of meta-analyses of twin studies of risk taking propensity across seven risk domains

Sample Measurement of Assessment method Age N Relation Effect Inclusion & study risk taking group _ gender size Natural/physical risk Sample & Measurement Assessment method Age N Relation_ Effect Inclusion study group gender size Canada general population sample (Vernon, Lee, Harris, & Jang, 1996) Sensation-seeking Alcohol effects 31.1± 115 MZ 0.26 Included questionnaire (AEQ; 11.4 Southwick, Steele, (18- Marlatt 86) & Lindell, 1981) subscale 61 DZ 0.16 Included The national community-based Australian Twin Registry (ATR) (Ellingson, Verges, Littlefield, Martin, & Slutske, 2013) Sensation-seeking Sensation seeking scale 37.7± 461 MZ-M 0.51 Included (ZSS; Zuckerman et al. 2.3 1964) 659 MZ-F 0.49 Included 403 DZ-M 0.33 Included 529 DZ-F 0.27 Included Minnesota Study of Twins Reared Apart (MISTRA) (Hur & Bouchard, 1997) Sensation seeking Sensation seeking scale 44.2 57 MZ 0.47 Included scale subscale 1 TAS (Zuckerman, (16- 1979) 77) 49 DZ 0.48 Included DIS 57 MZ 0.5 Included 49 DZ 0.1 Included BS 57 MZ 0.43 Included 49 DZ 0.16 Included ES 57 MZ 0.54 Included 49 DZ 0.28 Included Netherlands general population (Feij & Van Zuilen, 1984; Judith R. Koopmans, Boomsma, Heath, & van Doornen, 1995) TAS Dutch version of 17.7±2 260 MZ-M 0.62 Included Zuckerman's Sensation .26 Seeking Scale, form IV (Feij and van Zuilen, 1984). 348 MZ-F 0.63 Included 230 DZ-M 0.42 Included 304 DZ-F 0.31 Included 449 DZ-OS 0.25 Included ES 260 MZ-M 0.53 Included 348 MZ-F 0.6 Included 230 DZ-M 0.35 Included 304 DZ-F 0.29 Included 449 DZ-OS 0.25 Included BS 260 MZ-M 0.45 Included 348 MZ-F 0.55 Included 230 DZ-M 0.33 Included 304 DZ-F 0.34 Included 449 DZ-OS 0.24 Included DIS 260 MZ-M 0.59 Included 348 MZ-F 0.58 Included 230 DZ-M 0.42 Included 304 DZ-F 0.45 Included 449 DZ-OS 0.3 Included Netherlands Twin Register (Stoel, De Geus, & Boomsma, 2006) TAS Dutch version of 25.3±1 579 MZ-M 0.58 Included Zuckerman's Sensation 0.9 Seeking Scale, form IV (Feij and van Zuilen, 1984). 1029 MZ-F 0.62 Included

3 461 DZ-M 0.37 Included 632 DZ-F 0.32 Included 907 DZ-OS 0.19 Included DIS 579 MZ-M 0.59 Included 1029 MZ-F 0.52 Included 461 DZ-M 0.4 Included 632 DZ-F 0.31 Included 907 DZ-OS 0.28 Included BS 579 MZ-M 0.45 Included 1029 MZ-F 0.47 Included 461 DZ-M 0.3 Included 632 DZ-F 0.32 Included 907 DZ-OS 0.24 Included ES 579 MZ-M 0.6 Included 1029 MZ-F 0.55 Included 461 DZ-M 0.38 Included 632 DZ-F 0.34 Included 907 DZ-OS 0.24 Included (Vinkhuyzen, van der Sluis, & Posthuma, 2012) Experience seeking Questionnaire 46.61± 83 MZ 0.6 Included 12.40 (23– 75) 67 DZ 0.31 Included Finnish Population Register Center (PRC) (Viken, Kaprio, & Rose, 2007) Sensation seeking Sensation seeking scale 17 330 MZ-M 0.65 Included (SSS; Zuckerman, 1979) 495 MZ-F 0.6 Included 408 DZ-M 0.33 Included 422 DZ-F 0.35 Included Adult Russian Twin Study (ARTS) (Saudino et al., 1999) Monotony avoidance Karolinksa 42.23 79 MZ 0.54 Included Scales of Personality ± 8.93 (Shalling, Edman, & Asberg, 1983) 51 DZ 0.14 Included Norwegian Institute of Public Health (Vassend, Røysamb, & Nielsen, 2013) Excitement seeking NEO Personality 23-35 104 MZ 0.548 Included Inventory scale 78 DZ 0.219 Included Australian National Health and Medical Research Council (NH&MRC) volunteer adult twin panel (Andrew C Heath, Cloninger, & Martin, 1994) Novelty seeking short-form 54-item 41.58 396 MZ-M 0.35 Included version of the (25- Tridimensional 89) Personality Questionnaire (TPQ; Cloninger et al., 1991) 933 MZ-F 0.42 Included 222 DZ-M 0.06 Included 532 DZ-F 0.14 Included 564 DZ-OS 0.07 Included General population recruited by American Association of Retired Persons (AARP) (Heiman, Stallings, Hofer, & Hewitt, 2003) Novelty seeking 100-item Tridimensional 50-65 308 MZ-F 0.42 Included Personality Questionnaire (TPQ; Cloninger, 1987). 131 DZ-F 0.37 Included 66-89 269 MZ-F 0.47 Included 141 DZ-F 0.12 Included Colorado Longitudinal Twin Sample (LTS) and the Colorado Twin Registry (CTR; P.I.: J.K. Hewitt) (Heiman, Stallings, Young, & Hewitt, 2004) Novelty seeking 54-item self-administered 16-18 67 MZ-M 0.25 Excluded(f TPQ or sample (Heath et al., 1994). size) 80 MZ-F 0.37 Excluded 52 DZ-M 0.12 Excluded 43 DZ-F -0.27 Excluded

4 66 DZ-OS 0.16 Excluded Colorado Twin Registry (Hink et al., 2013) Novelty seeking TPQ/TCI 14.82± 290 MZ-M 0.40 Included 2.15 (12- 18) 345 MZ-F 0.38 Included 219 DZ-M 0.15 Included 211 DZ-F 0.15 Included 261 DZ-OS 0.09 Included Colorado Longitudinal Twin Study (LTS) (Young et al., 2009) Novelty seeking Cloninger’s 17.4±0 159 MZ 0.28 Included Tridimensional .62 Personality (16.5- Questionnaire—Short 20) Form (TPQ; Heath, Cloninger, & Martin, 1994) 134 DZ 0.14 Included Finn Twin 16 (B. S. Mustanski, Viken, Kaprio, & Rose, 2003) Excitement seeking Zuckerman’s Sensation- 18.5 239 MZ-M 0.56 Included Seeking Scales (SSS, Zuckerman, 1979) Disinhibition and Boredom Susceptibility subscales 412 MZ-F 0.52 Included 315 DZ-M 0.27 Included 354 DZ-F 0.26 Included Keio Twin Project (KTP), Japan (Ando et al., 2002) Novelty seeking Japanese version of 20 ± 182 MZ 0.17 Excluded Cloninger’s Temperament 3.3 (for sample and Character Inventory (14- size) (TCI) (Kijima et al., 28) 1996). 110 DZ 0.15 Exclude (Ando et al., 2004) Novelty seeking Japanese translation of the 20.06± 414 MZ 0.35 Included- Temperament and 3.79 average Character Inventory (TCI: (15- Kijima et al., 1996) 30) 203 DZ 0.12 Included- average population-based Italian Twin Register (ITR) (Brambilla et al., 2014) Novelty seeking 125-item version of the 40±12 161 MZ 0.37 Included Temperament (18- and Character 65) Inventory(TCI-125) (Cloninger et al.,1993;Urgesietal.,2012) . 106 DZ 0.06 Included Australian Twin Registry (Keller, Coventry, Heath, & Martin, 2005) Novelty seeking Temperament and 35±13. 729 MZ-M 0.42 Included Character Inventory 2 (18- (TCI) (Cloninger et al., 90) 1991). 1442 MZ-F 0.40 Included 533 DZ-M 0.09 Included 969 DZ-F 0.12 Included 1164 DZ-OS 0.12 Included The Swedish Twin study of Child and Adolescent Development (TCHAD) (Merwood, Asherson, & Larsson, 2013) Novelty seeking A short version of the 19.66 140 MZ-M 0.46 Included temperament and ± 0.46 Character Inventory (TCI: Cloninger et al., 1993)

5 214 MZ-F 0.47 Included 83 DZ-M 0.05 Included 145 DZ-F 0.01 Included 286 DZ-OS 0.08 Included Netherlands Twin Register (Romero‐Martínez, Moya‐Albiol, Vinkhuyzen, & Polderman, 2015) Experience seeking Subscale of sensation 40.60 81 MZ 0.60 Included seeking scale ± 12.38 67 DZ 0.27 Included Moral risk Sample & Measurement Assessment method Age N Relation_ Effect Inclusion study group gender size Swedish twin registry (Loewen et al., 2013) Dishonesty standard Questionnaire 60±0.0 1055 MZ 0.33 Included for 4 usual immoral 5 behavior 1102 DZ 0.17 Included (Campbell et al., 2009) Kohlberg’s theory of Questionnaire and 13-20 259 MZ 0.3 Included moral development: criminality records the Personal Interest Schema (DIT-PI) 183 DZ 0.13 Included Maintaining Norms 259 MZ 0.33 Included Schema (DIT-MN) 183 DZ 0.04 Included Post-Conventional 259 MZ 0.38 Included Schema(DIT-PC) 183 DZ 0.39 Included (Catherine Tuvblad, Narusyte, Grann, Sarnecki, & Lichtenstein, 2011) Rule-breaking Self-report delinquency 16-17 427 MZ-M 0.62 Included- behavior questionnaire(Ring, 1999) average 484 MZ-F 0.53 Included- average 311 DZ-M 0.71 Included- average 358 DZ-F 0.49 Included- average 298 DZ-OS 0.31 Included- average 19-20 279 MZ-M 0.43 Included- average 418 MZ-F 0.36 Included- average 169 DZ-M 0.58 Included- average 292 DZ-F 0.24 Included- average 202 DZ-OS 0.2 Included- average Tuvblad, Eley, and Lichtenstein (2005) Rule-breaking Self-report 16–17 203 MZ_M .70 Excluded(f behavior or smaller sample) 210 MZ_F .66 Excluded 161 DZ_M .54 Excluded 182 DZ_F .52 Excluded 333 DZ_OS .44 Excluded (Larsson et al., 2007) Rule-breaking Self-report 16–17 181 MZ_M .56 Excluded(f behavior or smaller size) 202 MZ_F .69 Excluded 131 DZ_M .47 Excluded 144 DZ_F .45 Excluded 298 DZ_OS .26 Excluded Minnesota Twin Family Study (Taylor, McGue, Iacono, & Lykken, 2000) Rule-breaking Self-report 17 143 MZ_M .58 Excluded behavior

6 180 MZ_F .46 Included 72 DZ_M .11 Excluded 91 DZ_F .48 Included Taylor, McGue, Iacono, and Lykken (2000) Rule-breaking Self-report 17 145 MZ_M .52 Included behavior 107 MZ_F .48 Excluded 77 DZ_M .15 Included 52 DZ_F .37 Excluded Finn Twin Vierikko, Pulkkinen, Kaprio, and Rose (2006) Aggression Teacher’s assessment 14 168 MZ_M .66 Included 196 MZ_F .72 Included 180 DZ_M .54 Included 168 DZ_F .58 Included 329 DZ_OS .21 Included Los Angeles area (Niv, Tuvblad, Raine, & Baker, 2013) Aggression Self-report 14-15 249 MZ-M 0.74 included- average 229 MZ-F 0.72 included- average 175 DZ-M 0.11 included- average 212 DZ-F 0.42 included- average 283 DZ-OS 0.52 included- average Rule-breaking 249 MZ-M 0.85 included- average 229 MZ-F 0.88 included- average 175 DZ-M 0.39 included- average 212 DZ-F 0.46 included- average 283 DZ-OS 0.56 included- average (Wang, Niv, Tuvblad, Raine, & Baker, 2013) Non-aggressive Self-report delinquency 16-18 189 MZ-M 0.61 included- antisocial behavior interview average 202 MZ-F 0.6 included- average 142 DZ-M 0.41 included- average 156 DZ-F 0.49 included- average 109 DZ-OS 0.49 included- average Aggressive antisocial 189 MZ-M 0.47 included- behavior average 202 MZ-F 0.27 included- average 142 DZ-M 0.2 included- average 156 DZ-F 0.43 included- average 109 DZ-OS 0.26 included- average Netherlands Twin Registry (NTR) (van der Aa, Rebollo-Mesa, Willemsen, Boomsma, & Bartels, 2009) Frequency of truancy A 6-point scale about how 19.78± 283 MZ-M 0.64 Included often they skipped lessons 3.12 during a whole day while (14.27 in high school - 28.25) 328 MZ-F 0.73 Included 232 DZ-M 0.42 Included 279 DZ-F 0.59 Included 227 DZ-OS 0.46 Included National Longitudinal Study of Adolescent Health (Add Health) (K. M. Beaver & J. C. Barnes, 2012) Drug selling behavior Times in the previous Adult 168 MZ 0.73 Excluded

7 (dichotomous) months they had sold (dichotomo marijuana or other drugs us variable) 244 DZ 0.20 Excluded Drug selling behavior 168 MZ 0.41 Included (continuous) 244 DZ 0.11 Included Swedish Twin Registry (K. Kendler et al., 2015) Criminal behavior Criminal records of 38.3±8 2798 MZ-M 0.728 Included Swedish Crime Register .1 38.2±8 3403 MZ-F 0.477 Included .2 40.7±8 2585 DZ-M 0.507 Included .4 40.4±8 2853 DZ-F 0.413 Included .5 37.4±1 8964 DZ-OS 0.282 Included 0.1 (K. S. Kendler et al., 2015) Criminal behavior Criminal records of 15-19 1746 MZ 0.79 Included- Swedish Crime Register average 1860 DZ 0.48 Included- average 20-24 1746 MZ 0.65 Included- average 1860 DZ 0.40 Included- average 25-29 1746 MZ 0.63 Included- average 1860 DZ 0.38 Included- average Financial risk Sample & Measurement Assessment method Age N Relation_ Effect Inclusion study group gender size The Swedish Twin Registry (Barnea, Cronqvist, & Siegel, 2010) Stock market Data from the Swedish 30-79 5421 MZ 0.298 included- participant Tax Agency average 1333 DZ 0.143 included- 1 average Share in equities 5421 MZ 0.307 included- average 1333 DZ 0.15 included- 1 average (Cesarini, Johannesson, Lichtenstein, Sandewall, & Wallace, 2010) Portfolio risk (risk 50.1 2747 MZ-M 0.29 Included- level of funds average invested) 48.7 3346 MZ-F 0.27 Included- average 52.8 3591 DZ-M 0.13 Included- average 51.8 3879 DZ-F 0.16 Included- average Standard deviation of 2747 MZ-M 0.27 Included- returns adjusted to average covariance between funds 3346 MZ-F 0.26 Included- average 3591 DZ-M 0.12 Included- average 3879 DZ-F 0.15 Included- average Weighted share of 2747 MZ-M 0.24 Included- equity funds in an average individual’s portfolio 3346 MZ-F 0.26 Included- average 3591 DZ-M 0.11 Included- average 3879 DZ-F 0.13 Included- average

8 (Beauchamp, Cesarini, & Johannesson, 2011) General risk attitude 10 points scale 61±4.5 1150 MZ 0.513 Excluded(f 7 or measure) 2362 DZ 0.216 Excluded Financial risk attitude 10 points scale 61±4.5 1150 MZ 0.433 included- 7 average 2362 DZ 0.249 included- average Health and retirement Questionnaire 1150 MZ 0.698 included- risk (asset allocation average after retirement) 2362 DZ 0.311 included- average Gain risk Questionnaire 1150 MZ 0.382 included- average 2362 DZ 0.131 included- average Loss risk Questionnaire 1150 MZ 0.353 included- average 2362 DZ 0.08 included- average (Calvet & Sodini, 2013) Risky share Government statistical Adult 2545 MZ 0.266 included- data average 5849 DZ 0.149 included- average Permanent income MZ 0.118 included- risk average DZ 0.013 included- average Transitory income MZ 0.137 included- risk average DZ 0.027 included- average (Cesarini, Dawes, Johannesson, Lichtenstein, & Wallace, 2009) Risky choice (six Questionnaire 34.8 319 MZ 0.222 included- choices between a average sure and risky option) 141 DZ 0.024 included- average Risk investment 319 MZ 0.304 included- (amount for risky average investment) 141 DZ 0.11 included- average Risk assessment (10- 319 MZ 0.384 included- point self-assessment average scale) 141 DZ -0.043 included- average The Swedish Twin Registry and TwinGene (Benjamin et al., 2012) Self-evaluation of risk 10-point questionnaire Adult 594 MZ-F 0.35 Included attitude 443 MZ-M 0.41 Included 636 DZ-F 0.13 Included 477 DZ-M 0.2 Included Australian Twin Registry Younger (Le, Miller, Slutske, & Martin, 2011) Choice between a Self-report to two 37.7 867 MZ 0.241 Included sure option and a questions risky option 1008 DZ 0.105 Included China Fujian, Beijing, Wuhan and Hefei (Zhong et al., 2009) Choice between a Questionnaire 30.8 167 MZ 0.57 Included sure option and a ±15.1 risky option 65 DZ 0.02 Included Minnesota Twin Registry (Zyphur, Narayanan, Arvey, & Alexander, 2009) Three questionnaire Questionnaire 36.7±1 111 MZ 0.63 Included items (reward .12

9 between three risky options) 89 DZ 0.16 Included Reproduction Sample & Measurement Assessment method Age N Relation_ Effect Inclusion study group gender size Australian National Health and Medical Research Council Twin Registry (ATR) (Verweij, Zietsch, Bailey, & Martin, 2009) Risky sexual behavior Risky sexual behavior 19-52 376 MZ-M 0.66 Included questionnaire, 8 items 666 MZ-F 0.6 Included 185 DZ-M 0.48 Included 312 DZ-F 0.43 Included 366 DZ-OS 0.18 Included (B. P. Zietsch, Verweij, Bailey, Wright, & Martin, 2010) Risky sexual behavior RSB questionnaire, 8 M 277 MZ-M 0.66 Excluded(f items 30.5±8 or smaller .3; sample F size) 31.1± 8.5 572 MZ-F 0.6 Excluded 156 DZ-M 0.48 Excluded 319 DZ-F 0.43 Excluded 307 DZ-OS 0.18 Excluded longitudinal Minnesota Twin Family Study (MTFS) (Huibregtse, Bornovalova, Hicks, McGue, & Iacono, 2011) Regular partners Questionnaire 24-29 691 MZ 0.17 Included M&F 391 DZ 0.13 Included Casual partners M 333 MZ-M 0.32 Included 178 DZ-M 0.01 Included Sex after drunk M 333 MZ-M 0.1 Included 178 DZ-M -0.11 Included Sex after drunk F 358 MZ-F 0.44 Included 213 DZ-F 0.21 Included Lifetime casual M 333 MZ-M 0.26 Included 178 DZ-M 0.14 Included Early pregnancy 691 MZ 0.14 Included M&F 391 DZ 0.04 Included National Longitudinal Study of Adolescent Health (Boutwell & Boisvert, 2014) Sexual promiscuity One question about 11-34 144 MZ-M 0.37 Included number of sexual partners 145 MZ-F 0.48 Included 131 DZ-M 0.35 Included 116 DZ-F 0.34 Included Finland’s Population Register Centre (B. Mustanski, Viken, Kaprio, Winter, & Rose, 2007) Age at first sexual Self-report 24.4±0 313 MZ-M 0.625 Included intercourse .84 472 MZ-F 0.671 Included 387 DZ-M 0.252 Included 414 DZ-F 0.392 Included 862 DZ-OS 0.292 Included Number of sexual 313 MZ-M 0.552 Included partners 472 MZ-F 0.483 Included 387 DZ-M 0.254 Included 414 DZ-F 0.282 Included 862 DZ-OS 0.279 Included Dichotomous scoring 313 MZ-M 0.907 Included of initiation or abstinence 472 MZ-F 0.864 Included 387 DZ-M 0.564 Included 414 DZ-F 0.613 Included 862 DZ-OS 0.384 Included Danish Twin Registry (Rodgers, Kohler, Kyvik, & Christensen, 2001) Number of children Self-report 35-41 646 MZ-M 0.29 Included

10 576 MZ-F 0.31 Included 1032 DZ-M 0.13 Included 964 DZ-F 0.13 Included Age at first pregnancy 650 MZ-M 0.23 Included try 576 MZ-F 0.39 Included 1046 DZ-M 0.06 Included 968 DZ-F 0.19 Included Murcia Twin Register (Colodro-Conde, Rijsdijk, & Ordoñana, 2013) Number of children Self-report 51.2±7 239 MZ 0.46 Included .4 (41- 68) 236 DZ 0.35 Included The Vietnam Era Twin Registry (Lyons et al., 2004) Age of initiation Self-report 44.6±2 1874 MZ-M 0.44 Included .8 (36- 55) 1498 DZ-M 0.24 Included Multiple partners Self-report 1874 MZ-M 0.60 Included 1498 DZ-M 0.49 Included Add Health (McHale, Bissell, & Kim, 2009) Risky sexual attitudes 5-point 7-item scale 16.74± 192 MZ 0.59 Included 1.6 16.58± 267 DZ 0.29 Included 1.68 Risky pregnancy 5-point 8-item scale 192 MZ 0.48 Included attitudes 267 DZ 0.40 Included Risky sexual behavior Self-report on number of 192 MZ 0.46 Included sexual partners 267 DZ 0.29 Included Australian National Health and Medical Research Council (Waldron et al., 2007) Age at first sexual Self-report on first 45.31± 1012 MZ-F 0.73 Included intercourse (Twin- sexual intercourse 12.47 1981) (28- 92) 607 DZ-F 0.559 Included Age at first sexual 30.47± 759 MZ-F 0.70 Included intercourse (Twin- 2.45 1989) (22- 36) 569 DZ-F 0.55 Included Age at first 759 MZ-F 0.69 Included consensual sexual intercourse (Twin- 1989) 569 DZ-F 0.55 Included Teenage pregnancy Self-report on pregnancy 1012 MZ-F 0.53 Included (Twin-1981) before age 20 607 DZ-F 0.21 Included Teenage pregnancy 759 MZ-F 0.54 Included (Twin-1989) 569 DZ-F 0.37 Included Finnish community-based twin siblings (Brendan P Zietsch, Westberg, Santtila, & Jern, 2015) Extrapair mating Self-report on number of 29.8±6 101 MZ-M 0.67 Included extrapair mating .4 (18- 49) 370 MZ-F 0.43 Included 239 DZ-M -0.07 Included 973 DZ-F 0.08 Included 697 DZ-OS 0.03 Included Australian National Health and Medical Research Council Twin Register (ATR) (Bailey, Kirk, Zhu, Dunne, & Martin, 2000) Sociosexuality Self-report of the 31±8 304 MZ-M 0.52 Included sociosexuality scale (19- scores 51) 650 MZ-F 0.55 Included

11 179 DZ-M 0.35 Included 364 DZ-F 0.32 Included 346 DZ-OS 0.16 Included National Longitudinal Study of Adolescent Health (Carlson, Mendle, & Harden, 2014) Age at first sex Self-report 17.16± 281 MZ 0.56 Included 2.88 (11- 30) 246 DZ 0.33 Included Vietnam Era Twin Registry (Lyons et al., 2004) Age initiation Self-report of question in 44.6±2 1874 MZ 0.44 Included- DSM-Ⅲ .8 (36- average 55) 1498 DZ 0.24 Included- average Multiple partners Self-report of question in 1874 MZ 0.60 Included- DSM-Ⅲ average 1498 DZ 0.49 Included- average Cooperation/competition Sample & Measurement Assessment method Age N Relation_ Effect Inclusion study group gender size Montreal area general population sample (Brendgen, Girard, Vitaro, Dionne, & Boivin, 2013b) Aggression risk Peer nominations, 10.04± 110 MZ 0.34 Excluded(f questionnaire 0.26 or age) 87 DZ 0.09 Excluded(f or age) (Brendgen, Girard, Vitaro, Dionne, & Boivin, 2013a) Relational aggression Peer nominations 15-18 112 MZ 0.23 Included 80 DZ 0.02 Included Swedish Twin Registry (Wallace, Cesarini, Lichtenstein, & Johannesson, 2007) Ultimatum game Laboratory experiment 22-47 258 MZ 0.39 included responder behavior 71 DZ -0.04 included Minnesota Twin Registry (McGue & Lykken, 1992) Familial risk for Questionnaire 34-53 275 MZ-M 0.531 included divorce 447 MZ-F 0.55 included 288 DZ-M 0.205 included 506 DZ-F 0.196 included Colorado Longitudinal Twin Sample (LTS) (Button et al., 2007) Delinquent peer Self-report 15.24± 254 MZ-M 0.6 included affiliation 2.21 (11- 18) 299 MZ-F 0.65 included 175 DZ-M 0.47 included 177 DZ-F 0.49 included 206 DZ-OS 0.21 included Add Health (Boisvert, Boutwell, Vaske, & Newsome, 2013) Delinquent Self-report Adult 289 MZ 0.69 included- peers(wave 1) average 452 DZ 0.32 included- average Delinquent 289 MZ 0.63 included- peers(wave 2) average 452 DZ 0.29 included- average National Longitudinal Survey of Youth (Connolly & Beaver, 2014) Gang involvement Self-report 26-32 27 MZ 0.69 Included 932 DZ 0.38 Included Minnesota Twin and Family Study (MTFS) (Tarantino et al., 2014) Trait deviant peers Self-report 15 418 MZ 0.64 Included

12 228 DZ 0.60 Included 18 372 MZ 0.73 Included 204 DZ 0.57 Included 21 381 MZ 0.62 Included 214 DZ 0.43 Included Swedish Twin Registry at Karolinska Institutet. (Cesarini et al., 2008) Trust (fraction sent in Laboratory experiment 22-47 516 MZ 0.25 Included the trust game) 142 DZ -0.01 Included Trustworthiness 516 MZ 0.29 Included (fraction returned in the trust game) 142 DZ 0.18 Included Swedish Twin Registry (Oskarsson, Dawes, Johannesson, & Magnusson, 2012) Social trust A 10-point question on Adult 463 MZ-M 0.35 Included social trust 495 MZ-F 0.37 Included 667 DZ-M 0.19 Included 725 DZ-F 0.19 Included California annual Twins Days Festival in Twinsburg (Cesarini et al., 2008) Trust (fraction sent in Laboratory experiment Adult 556 MZ 0.13 Included- the trust game) ， average Older than 18 150 DZ -0.07 Included- average Trustworthiness 556 MZ 0.26 Included- (fraction returned in average the trust game) 150 DZ 0.06 Included- average Australian general population (Sturgis et al., 2010) Social trust 4 items of NEO-PI-R 17-33 184 MZ 0.355 Included personality inventory 220 DZ 0.21 Included The Keio Twin Study (KTS) (Hiraishi, Shikishima, Yamagata, & Ando, 2015) Cooperativeness Public goods game, group 25.42± 98 MZ 0.05 Included experiment 4.27 (18- 37) 29 DZ -0.45 Included Netherlands Twin Register (Van Lange, Vinkhuyzen, & Posthuma, 2014) Trust in others Trust-in-others scale 45.3±1 491 MZ 0.16 Included 4.1 (17- 70) 521 DZ 0.04 Included The nationwide Danish Twin Register (Pedersen et al., 2015) Blood donation Computerized records of 17-27 65 MZ-M 0.79 Included blood donors from The Scandinavian Donation and Transfusion (SCANDAT) database 127 MZ-F 0.82 Included 139 DZ-M 0.55 Included 254 DZ-F 0.56 Included Safety Sample & Measurement Assessment method Age N Relation_ Effect Inclusion study group gender size Australian National Health and Medical Research Council (A. C. Heath & Martin, 1994) Problem drinking Questionnaire 18-30 321 MZ-M 0.44 Included 726 MZ-F 0.43 Included

13 178 DZ-M 0.43 Included 406 DZ-F 0.24 Included 454 DZ-OS 0.31 Included Minnesota Twin Family Study (Han, McGue, & Iacono, 1999) Alcohol use Interview 17-18 179 MZ-M 0.84 Included 148 MZ-F 0.79 Included 97 DZ-M 0.57 Included 77 DZ-F 0.72 Included Netherlands Twin Register (Huppertz et al., 2014) Exercise behavior Questionnaire 18-50 189 MZ-M 0.45 Included 512 MZ-F 0.45 Included 81 DZ-M 0.21 Included 248 DZ-F 0.21 Included 243 DZ-OS 0.15 Included Dutch twins (Judith R Koopmans, Slutske, Van Baal, & Boomsma, 1999) Religious alcohol use Questionnaire 17.8±3 95 MZ-M 0.93 Included initiation .1 (12- 26) 114 MZ-F 0.87 Included 71 DZ-M 0.82 Included 97 DZ-F 0.9 Included 146 DZ-OS 0.75 Included Nonreligious alcohol Questionnaire 92 MZ-M 0.88 Included use initiation 99 MZ-F 0.95 Included 73 DZ-M 0.61 Included 92 DZ-F 0.72 Included 132 DZ-OS 0.75 Included Mid-Atlantic Twin Registry (Anum, Silberg, & Retchin, 2014) Drunk driving Field study 21-49 688 MZ-M 0.54 Included 834 MZ-F 0.58 Included 459 DZ-M 0.18 Included 648 DZ-F 0.35 Included 1882 DZ-OS -0.01 Included National Longitudinal Study of Adolescent Health (Quinn & Harden, 2013) Drunk driving self-report 12-33 278 MZ 0.68 Included- average 239 DZ 0.42 Included- average Alcohol dependence 278 MZ 0.36 Included- symptoms average 239 DZ 0.11 Included- average (early)Age at first 278 MZ 0.57 Included- drink average 239 DZ 0.32 Included- average Adolescent alcohol 278 MZ 0.55 Included- use average 239 DZ 0.35 Included- average Adolescent binge 278 MZ 0.52 Included- drinking average 239 DZ 0.28 Included- average Adult alcohol use 278 MZ 0.37 Included- average 239 DZ 0.26 Included- average Adult binge drinking 278 MZ 0.46 Included- average 239 DZ 0.2 Included- average (K. M. Beaver & J. Barnes, 2012) Frequency of drunk Self-report 24-32 213 MZ 0.59 included- drinking average 332 DZ 0.09 included-

14 average Australian NH&MRC Twin Registry (Martin & Boomsma, 1989) Willingness to drive Self-report 23 37 MZ 0.61 Included- at 1h after alcohol (18- average 34) 34 DZ 0.49 Included- average Willingness to drive 37 MZ 0.42 Included- at 2h after alcohol average 34 DZ 0.46 Included- average Willingness to drive 37 MZ 0.74 Included- at 3h after alcohol average 34 DZ 0.05 Included- average FinnTwin16 (FT16) (Dick, Meyers, Rose, Kaprio, & Kendler, 2011) Frequency of drinking Self-report 24.4±1 378 MZ-F 0.59 Included .5 (22.8- 27.2) 315 DZ-F 0.43 Included 287 MZ-M 0.75 Included 398 DZ-M 0.47 Included Frequency*quantity 378 MZ-F 0.45 Included 315 DZ-F 0.3 Included 287 MZ-M 0.61 Included 398 DZ-M 0.37 Included Frequency of heavy 378 MZ-F 0.54 Included drinking 315 DZ-F 0.34 Included 287 MZ-M 0.64 Included 398 DZ-M 0.42 Included Frequency of 378 MZ-F 0.64 Included intoxication 315 DZ-F 0.38 Included 287 MZ-M 0.65 Included 398 DZ-M 0.45 Included Maximum drinks 378 MZ-F 0.55 Included 315 DZ-F 0.35 Included 287 MZ-M 0.65 Included 398 DZ-M 0.29 Included The Malmo-modified 378 MZ-F 0.55 Included Michigan Alcoholism Screening Test 315 DZ-F 0.34 Included 287 MZ-M 0.63 Included 398 DZ-M 0.52 Included Rutgers Alcohol 378 MZ-F 0.43 Included Problem Index (RAPI) 315 DZ-F 0.23 Included 287 MZ-M 0.52 Included 398 DZ-M 0.25 Included Virginia Twin Registry (Kendler, Heath, Neale, Kessler, & Eaves, 1992) Alcoholism Self-report 30.1±7 590 MZ 0.53 Included .6 (17- 55) 440 DZ 0.15 Included Gambling USA general population sample (Blanco, Myers, & Kendler, 2012) DSM-III-R Web-based questionnaire 25.4±1 414 MZ 0.76 Included pathological 1.7 gambling symptoms and disorder 159 DZ 0.57 Included Vietnam Era Twin Registry (Eisen et al., 1998) DSM-III-R Telephone interview 33-53 1869 MZ-M 0.51 Included-

15 pathological average gambling symptoms and disorder 1490 DZ-M 0.21 Included- average (Giddens, Xian, Scherrer, Eisen, & Potenza, 2011) DSM-III-R Telephone interview 42.0±2 1874 MZ-M 0.62 Included- pathological .8 average gambling symptoms and disorder 1498 DZ-M 0.40 Included- average (Potenza, Xian, Shah, Scherrer, & Eisen, 2005) DSM-III-R Telephone interview 42.0±2 1874 MZ-M 0.62 Excluded(f pathological .8 or same gambling symptoms date) and disorder 1498 DZ-M 0.40 Excluded (Xian, Giddens, Scherrer, Eisen, & Potenza, 2014) Life-time DSM-III-R Interview 42.0±2 1874 MZ-M 0.49 Included- diagnoses .8 average 1498 DZ-M 0.19 Included- average Australian Twin Registry Younger (W. S. Slutske, Zhu, Meier, & Martin, 2011) DSM-IV DG Telephone interview 32-43 347 MZ-M 0.49 Included- average 520 MZ-F 0.55 Included- average 227 DZ-M 0.21 Included- average 367 DZ-F 0.21 Included- average 414 DZ-OS 0.22 Included- average South Oaks gambling Telephone interview 347 MZ-M 0.64 Included- screen average 520 MZ-F 0.49 Included- average 227 DZ-M 0.19 Included- average 367 DZ-F 0.28 Included- average 414 DZ-OS 0.16 Included- average (Richmond-Rakerd, Slutske, Heath, & Martin, 2014) DSM-IV DG Telephone interview 32-43 347 MZ-M 0.49 Excluded(f or same data) 520 MZ-F 0.55 Excluded 227 DZ-M 0.21 Excluded 367 DZ-F 0.21 Excluded 414 DZ-OS 0.22 Excluded (W. S. Slutske, Ellingson, Richmond-Rakerd, Zhu, & Martin, 2013) DSM-IV DG Structured telephone 32–43 347 MZ-M 0.49 Excluded (categorical) interview 520 MZ-F 0.53 Excluded 227 DZ-M 0.24 Excluded 367 DZ-F 0.22 Excluded 414 DZ-OS 0.23 Excluded DSM-IV DG 347 MZ-M 0.57 Included- (continuous) average 520 MZ-F 0.57 Included- average 227 DZ-M 0.3 Included- average 367 DZ-F 0.28 Included- average 414 DZ-OS 0.15 Included- average (W. S. Slutske et al., 2009) Gambling Structured telephone 37.7±0 867 MZ 0.56 Included involvement for all 11 interview ; questionnaire .04

16 Gambling activities (32– involvement 43) 1008 DZ 0.32 Included Versatility 867 MZ 0.58 Included 1008 DZ 0.28 Included Max 867 MZ 0.48 Included frequency(days/year) 1008 DZ 0.31 Included Max spent($/day) 867 MZ 0.58 Included 1008 DZ 0.31 Included National Longitudinal Study of Adolescent Health (W. S. Slutske & Richmond-Rakerd, 2014) Lottery In-person interview 18–28 111 MZ-M 0.62

130 MZ-F 0.44 107 DZ-M 0.64 93 DZ-F 0.62 156 DZ-OS 0.55 Casino tables or video 111 MZ-M 0.51 games 130 MZ-F 0.42 107 DZ-M 0.75 93 DZ-F 0.51 156 DZ-OS 0.57 Other gambling 111 MZ-M 0.35 130 MZ-F 0.46 107 DZ-M 0.19 93 DZ-F 0.29 156 DZ-OS 0.38 Any gambling 111 MZ-M 0.41 130 MZ-F 0.50 107 DZ-M 0.44 93 DZ-F 0.59 156 DZ-OS 0.38 Gambling activity 111 MZ-M 0.4 Included – count average 130 MZ-F 0.47 Included – average 107 DZ-M 0.39 Included – average 93 DZ-F 0.49 Included – average 156 DZ-OS 0.46 Included – average Los Angeles area (C. Tuvblad et al., 2013) Iowa Gambling Task Laboratory experiment 11-13 177 MZ 0.26 Excluded(f or age) 166 DZ 0.14 Excluded(f or age) 14-15 348 MZ 0.07 Included 473 DZ 0.12 Included 16-18 198 MZ 0.33 Included 251 DZ 0.16 Included United States (Winters & Rich, 1998) High-action Questionnaire 26.1 75 MZ 0.56 Included games(including lottery etc.) frequency 80 DZ 0.25 Included Non-high-action Questionnaire 75 MZ 0.57 Included games (including informal cards etc.) frequency 80 DZ 0.40 Included American general population (Anokhin, Golosheykin, Grant, & Heath, 2009) BART task Laboratory experiment, 12.5±0 169 MZ 0.3 Excluded(f longitudinal study .21 or age) 120 DZ 0.01 Excluded(f or age) 83 DZ-OS 0.24 Excluded(f

17 or age) 14.6±0 98 MZ 0.6 Included .24 65 DZ 0.19 Included 60 DZ-OS 0.08 Included Quebec Newborn Twin Registry (Vitaro et al., 2014) South Oaks Gambling Self-rating questionnaire 13 160 MZ 0.55 Included Screen for adolescents (SOGS- RA) frequency of involvement in gambling 119 DZ 0.18 Included Australian Twin Registry Cohort Ⅱ (Wendy S Slutske, Deutsch, Statham, & Martin, 2015) Gambling frequency Telephone interview 37.7 319 MZ-M 0.50 Included- for 11 different average gambling activities in past year 479 MZ-F 0.45 Included- average 211 DZ-M 0.27 Included- average 339 DZ-F 0.31 Included- average 376 DZ-OS 0.16 Included- average Disordered gambling DSM-5 diagnosis 37.7 319 MZ-M 0.42 Included- average 479 MZ-F 0.42 Included- average 211 DZ-M 0.23 Included- average 339 DZ-F 0.25 Included- average 376 DZ-OS 0.16 Included- average

Note. MZ, DZ represent monozygotic twins, dizygotic twins respectively. The -M, -F, or -OS indicates that the twins in question are male-male pairs, female-female pairs, and opposite sex pairs respectively. N equals number of twin pairs. The inclusion column indicates whether the study was included but the effect size was averaged (i.e., “included-averaged”), whether the study was included because the sample was the largest available in those data or because the sample was independent (i.e., listed as “included”), or whether the study was excluded (i.e., “excluded”). The reason for “excluded” was explain in the brackets.

18 Table S4. The moderation effect of nation/culture in the meta-analyses

Domain χ² df p-value AIC a² c² e² Gambling Parameters free 331.952 96 <.001 139.952 USA 0.49 0.03 0.48 European 0.52 0.00 0.48 Parameters constrained 332.804 99 <.001 134.804 0.52 0.00 0.48 Difference in χ² 0.852 3 0.837 -5.148 Natural/Physical risk Parameters free 220.093 165 0.003 -109.907 USA 0.39 0.00 0.61 European 0.50 0.00 0.5 Parameters constrained 252.112 168 <0.001 -83.888 0.49 0.00 0.51 Difference in χ² 32.019 3 <0.001 26.019 Cooperation/competition Parameters free 459.546 99 <0.001 261.546 USA 0.41 0.11 0.48 European 0.24 0.10 0.66 Parameters constrained 553.392 102 <0.001 349.342 0.3 0.12 0.58 Difference in χ² 93.846 3 <0.001 87.846 Reproduction Parameters free 590.608 120 <0.001 350.608 USA 0.3 0.19 0.51 European 0.52 0.00 0.48 Parameters constrained 633.704 123 <0.001 387.704 0.5 0.01 0.49 Difference in χ² 43.096 3 <0.001 37.096 Moral risk Parameters free 1101.82 105 <.001 891.820 USA 0.46 0.09 0.45 European 0.45 0.13 0.42 Parameters constrained 1104.65 108 <.001 888.650 0.45 0.13 0.42 Difference in χ² 2.83 3 0.419 -3.170 Safety Parameters free 707.788 90 <0.001 527.788 USA 0.54 0.00 0.46 European 0.32 0.19 0.49 Parameters constrained 734.279 93 <0.001 548.279 0.53 0.00 0.47 Difference in χ² 26.491 3 <0.001 20.491