Educational Differences in Completed Fertility: A Behavioral Genetic Study of Finnish Male and Female Twins

Abstract

Despite the large body of research on educational differences in fertility, how genetic and environmental influences may contribute to educational differences in completed fertility is not well understood. This study examines the association between educational level and completed fertility in a sample of Finnish male and female twins born between 1950 and 1957 with register-based fertility follow-up until 2009. The results show that poorly educated men and highly educated women are least likely to have any children and have lower completed fertility in general. Behavioral genetics analysis suggests that the association between education and having any children in both sexes is influenced by factors shared by co-twins and that these factors are genetic rather than common environmental. No evidence of a causal pathway between education and having any children independent of these shared influences is found. These findings suggest that familial factors may play a role in the process through which educational differences in completed fertility are formed.

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Notes

  1. 1.

    The sex-specific categorization of the educational variable is based on the preceding results: the association between education and fertility was nonlinear in both sexes with these specific cut-off points of the variable scale, thus showing a threshold effect.

  2. 2.

    Tetrachoric correlation refers to correlations calculated for dichotomous variables from an underlying assumed standard normal distribution in order to estimate either covariance between co-twins across two traits (cross-twin/cross-trait covariance) or twin-pair resemblance in a trait (cross-twin/within-trait covariance).

  3. 3.

    The genetic correlation (r A) is calculated by \( {r_A}={{{{{{\operatorname{cov}}}_{{A\left( {Edu,Child} \right)}}}}} \left/ {{\left( {\sqrt{{{{{\operatorname{var}}}_{{A\left( {Edu} \right)}}}}}\times \sqrt{{{{{\operatorname{var}}}_{{A\left( {Child} \right)}}}}}} \right)}} \right.} \), where A refers to genetic factors, Edu refers to educational level, and Child refers to having any children. The common (r C) and unique (r E) environmental correlation is calculated in the same way except that C / E replaces A.

References

  1. Andersson, G., Rønsen, M., Knudsen, L. B., Lappegård, T., Neyer, G., Skrede, K., . . . Vikat, A. (2009). Cohort fertility patterns in the Nordic countries. Demographic Research, 20(article 14), 313–352. doi:10.4054/DemRes.2009.20.14

  2. Becker, G. S. (1981). A treatise on the family. Cambridge, MA: Harvard University Press.

    Google Scholar 

  3. Becker, G. S., & Lewis, G. H. (1973). On the interaction between the quantity and quality of children. Journal of Political Economy, 81, 279–288.

    Article  Google Scholar 

  4. Billari, F. C., & Philipov, D. (2004). Education and the transition to motherhood: A comparative analysis of Western Europe (European Demographic Research Paper 2004/3). Vienna: Vienna Institute of Demography, Austrian Academy of Sciences.

  5. Blossfeld, H.-P., & Huinink, J. (1991). Human capital investments or norms of role transition? How woman’s schooling and career affect the process of family formation. American Journal of Sociology, 97, 143–168.

    Article  Google Scholar 

  6. Boomsma, D., Busjahn, A., & Peltonen, L. (2002). Classical twin studies and beyond. Nature Reviews Genetics, 3, 872–882.

    Article  Google Scholar 

  7. Booth, A. L., & Kee, H. J. (2009). Birth order matters: The effect of family size and birth order on educational attainment. Journal of Population Economics, 22, 367–397.

    Article  Google Scholar 

  8. Cohen, J. E., Kravdal, Ø., & Keilman, N. (2011). Childbearing impeded education more than education impeded childbearing among Norwegian women. Proceedings of the National Academy of Sciences of the United States of America, 108, 11830–11835.

    Article  Google Scholar 

  9. Dearden, K. A., Hale, C. B., & Woolley, T. (1995). The antecedents of teen fatherhood: A retrospective case–control study of Great Britain youth. American Journal of Public Health, 85, 551–554.

    Article  Google Scholar 

  10. Fieder, M., & Huber, S. (2007). The effects of sex and childlessness on the association between status and reproductive output in modern society. Evolution and Human Behavior, 28, 392–398.

    Article  Google Scholar 

  11. Fu, H., & Goldman, N. (1996). Incorporating health into models of marriage choice: Demographic and sociological perspectives. Journal of Marriage and the Family, 58, 740–758.

    Article  Google Scholar 

  12. Gauthier, A. H. (1998). The state and the family: A comparative analysis of family policies in industrialized countries. Oxford, UK: Clarendon Press.

    Google Scholar 

  13. Goodman, A., & Koupil, I. (2009). Social and biological determinants of reproductive success in Swedish males and females born 1915–1929. Evolution and Human Behavior, 30, 329–341.

    Article  Google Scholar 

  14. Gustafsson, S. (2001). Optimal age at motherhood. Theoretical and empirical considerations on postponement of maternity in Europe. Journal of Population Economics, 14, 224–247.

    Google Scholar 

  15. Hagestad, G. O., & Call, V. R. (2007). Pathways to childlessness: A life course perspective. Journal of Family Issues, 28, 1338–1361.

    Article  Google Scholar 

  16. Hakim, C. (2000). Work-lifestyle choices in the 21st century. Preference theory. New York: Oxford University Press.

    Google Scholar 

  17. Havén, H. (1999). Education in Finland 1999. Statistics and indicators. SVT education 1999:4. Statistics Finland. Helsinki, Finland: University Press.

    Google Scholar 

  18. Hoem, J. M. (1986). The impact of education on modern family-union initiation. European Journal of Population, 2, 113–133.

    Article  Google Scholar 

  19. Hoem, J. M., Neyer, G., & Andersson, G. (2006a). The relationship between educational field, educational level, and childlessness among Swedish women born in 1955–59. Demographic Research, 14(article 15), 331–380. doi:10.4054/DemRes.2006.14.15

    Article  Google Scholar 

  20. Hoem, J. M., Neyer, G., & Andersson, G. (2006b). Educational attainment and ultimate fertility among Swedish women born in 1955–59. Demographic Research, 14(article 16), 381–404. doi:10.4054/DemRes.2006.14.16

    Article  Google Scholar 

  21. Hofferth, S. I., Reid, L., & Mott, F. L. (2001). The effects of early childbearing on schooling over time. Family Planning Perspectives, 33, 259–267.

    Article  Google Scholar 

  22. Hoffman, S. D., Foster, E. M., & Furstenberg, F. F. (1993). Reevaluating the costs of teenage childbearing. Demography, 30, 1–13.

    Article  Google Scholar 

  23. Hopcroft, R. L. (2006). Sex, status, and reproductive success in the contemporary United States. Evolution and Human Behavior, 27, 104–120.

    Article  Google Scholar 

  24. Kaprio, J., & Koskenvuo, M. (2002). Genetic and environmental factors in complex diseases. The older Finnish twin cohort. Twin Research, 5, 358–365.

    Google Scholar 

  25. Kaprio, J., Koskenvuo, M., Artimo, M., Sarna, S., & Rantasalo, I. (1979). Baseline characteristics of the Finnish Twin Registry. Materials, methods, representativeness, and results for variables special to twin studies (Publications in Public Health M47). Helsinki, Finland: National Public Health Institutes in Helsinki, Kuopio, Oulu, Tampere and Turku.

  26. Kartiovaara, L., & Säkkinen, S. (2007). Lasten muualla asuvat vanhemmat [The absent parents of children]. In Suomalainen Lapsi [The Finnish child] (pp. 109–127). Väestö 2007. Helsinki, Finland: Tilastokeskus & Stakes.

  27. Keizer, R., Dykstra, P. A., & Jansen, M. D. (2008). Pathways into childlessness: Evidence of gendered life course dynamics. Journal of Biosocial Science, 40, 863–878.

    Article  Google Scholar 

  28. Kiernan, K. E. (1989). Who remains childless? Journal of Biosocial Science, 21, 387–398.

    Article  Google Scholar 

  29. Kiernan, K. E., & Diamond, I. (1983). The age at which childbearing starts—A longitudinal study. Population Studies, 37, 363–380.

    Google Scholar 

  30. Kohler, H.-P., Behrman, J. R., & Schnittker, J. (2010). Social science methods for twin data: Integrating causality, endowments and heritability (PSC Working Paper Series, 10-06). Philadelphia: University of Pennsylvania, Population Studies Center.

  31. Kohler, H.-P., & Christensen, K. (2000). Genetic influences on fertility behavior: Findings from a Danish twin study, 1910–1923. In J. L. Rodgers, D. C. Rowe, & W. B. Miller (Eds.), Genetic influences on fertility and sexuality. Theoretical and empirical contributions from the biological and behavioral sciences (pp. 67–84). Norwell, MA: Kluwer Academic.

    Google Scholar 

  32. Kohler, H.-P., & Rodgers, J. L. (2003). Education, fertility, and heritability: Explaining a paradox. In K. W. Wachter & R. A. Bulatao (Eds.), Offspring: Human fertility behavior in biodemographic perspective (pp. 46–90). Washington, DC: The National Academies Press.

    Google Scholar 

  33. Kohler, H.-P., Rodgers, J. L., & Christensen, K. (1999). Is fertility behavior in our genes? Findings from a Danish twin study. Population and Development Review, 25, 253–288.

    Article  Google Scholar 

  34. Kontula, O. (2008). The influence of education and family policies on age at first birth. In C. Höhn, D. Avramov, & I. E. Kotowska (Eds.), People, population change and policies. Lessons from the Population Policy Acceptance Study. Volume 1: Family change (pp. 259–75). Dordrecht, The Netherlands: Springer.

    Google Scholar 

  35. Koskenvuo, M., Sarna, S., Kaprio, J., & Lönnqvist, J. (1979). Cause-specific mortality by marital status and social class in Finland during 1969–1971. Social Science & Medicine, 13, 691–697.

    Google Scholar 

  36. Kravdal, Ø. (2001). The high fertility of college educated women in Norway. An artifact of the separate modelling of each parity transition. Demographic Research, 5(article 6), 187–216. doi:10.4054/DemRes.2001.5.6

    Article  Google Scholar 

  37. Kravdal, Ø. (2007). Effects of current education on second- and third birth rates among Norwegian women and men born in 1964: Substantive interpretations and methodological issues. Demographic Research, 17(article 9), 211–246. doi:10.4054/DemRes.2007.17.9

    Article  Google Scholar 

  38. Kravdal, Ø., & Rindfuss, R. R. (2008). Changing relationships between education and fertility: A study of women and men born 1940–1964. American Sociological Review, 73, 854–873.

    Article  Google Scholar 

  39. Lappegård, T., & Rønsen, M. (2005). The multifaceted impact of education on entry into motherhood. European Journal of Population, 21, 31–49.

    Article  Google Scholar 

  40. Lestaeghe, R. (1983). A century of demographic and cultural change in Western Europe: An exploration of underlying dimensions. Population and Development Review, 9, 411–435.

    Article  Google Scholar 

  41. Liefbroer, A. C., & Corijn, M. (1999). Who, what, where, and when? Specifying the impact of educational attainment and labour force participation on family formation. European Journal of Population, 15, 45–75.

    Article  Google Scholar 

  42. Martín-García, T., & Baizán, P. (2006). The impact of the type of education and of educational enrolment on first births. European Sociological Review, 22, 259–275.

    Article  Google Scholar 

  43. McElroy, S. W. (1996). Early childbearing, high school completion, and college enrollment: Evidence from 1980 high school sophomores. Economics of Education Review, 15, 303–324.

    Article  Google Scholar 

  44. Mealey, L., & Segal, N. L. (1993). Heritable and environmental variables affect reproduction-related behaviors but not ultimate reproductive success. Personality and Individual Differences, 14, 783–794.

    Article  Google Scholar 

  45. Miller, W. B. (1992). Traits and developmental experiences as antecedents of childbearing motivation. Demography, 29, 265–285.

    Article  Google Scholar 

  46. Miller, W. B. (1994). Childbearing motivations, desires, and intentions: A theoretical framework. Genetic, Social and general Psychology Monologues, 120, 223–253.

    Google Scholar 

  47. Miller, W. B., Bard, D. E., & Pasta, D. J. (2010). Biodemographic modeling of the links between fertility motivation and fertility outcomes in the NLSY79. Demography, 47, 393–414.

    Article  Google Scholar 

  48. Monstad, K., Propper, C., & Salvanes, K. G. (2008). Education and fertility: Evidence from a natural experiment. Scandinavian Journal of Economics, 110, 827–852.

    Article  Google Scholar 

  49. Morgan, S. P., & Rindfuss, R. R. (1999). Reexamining the link of early childbearing to marriage and to subsequent fertility. Demography, 36, 59–75.

    Article  Google Scholar 

  50. Murphy, M., & Knudsen, L. B. (2002). The intergenerational transmission of fertility in contemporary Denmark: The effects of number of children (full and half), birth order, and whether male or female. Population Studies, 56, 235–248.

    Article  Google Scholar 

  51. Neale, M. C. (2003). Mx: Statistical modeling. Richmond, VA: Department of Psychiatry.

    Google Scholar 

  52. Neale, M. C., & Cardon, L. R. (1992). Methodology for genetic studies on twins and families. Dordrecht, The Netherlands: Kluwer Academic.

    Book  Google Scholar 

  53. Neale, M. C., Walters, E., Heath, A. D., Kessler, R. C., Pérusse, D., Eaves, L. J., & Kendler, K. S. (1994). Depression and parental bonding: Cause, consequence, or genetic covariance? Genetic Epidemiology, 11, 503–522.

    Article  Google Scholar 

  54. Neiss, M., Rowe, D. C., & Rodgers, J. L. (2002). Does education mediate the relationship between IQ and age of first birth? A behavioural genetic analysis. Journal of Biosocial Science, 34, 259–275.

    Article  Google Scholar 

  55. Nettle, D., & Pollet, T. V. (2008). Natural selection on male wealth in humans. The American Naturalist, 172, 658–666.

    Article  Google Scholar 

  56. Nikander, T. (1995). Suomalaismiehen perheellistyminen [The family formation of a Finnish man]. SVT Väestö 1995:1. Helsinki, Finland: Tilastokeskus.

  57. Oppenheimer, V. K. (1988). A theory of marriage timing. American Journal of Sociology, 94, 563–591.

    Article  Google Scholar 

  58. Oppenheimer, V. K., & Lew, V. (1995). American marriage formation in the 1980s: How important was women’s economic independence? In K. O. Mason & A. M. Jensen (Eds.), Gender and family change in industrialized countries (pp. 105–138). Oxford, UK: Clarendon Press.

    Google Scholar 

  59. Parr, N. J. (2005). Family background, schooling and childlessness in Australia. Journal of Biosocial Science, 37, 229–243.

    Article  Google Scholar 

  60. Parr, N. J. (2009). Childlessness among men in Australia. Population Research and Policy Review, 29, 319–338.

    Article  Google Scholar 

  61. Phillips, D. I., Handelsman, D. J., Eriksson, J. G., Forsén, T., Osmond, C., & Barker, D. J. (2001). Prenatal growth and subsequent marital status: Longitudinal study. British Medical Journal, 322, 771.

    Article  Google Scholar 

  62. Pollak, R. A., & Watkins, S. C. (1993). Cultural and economic approaches to fertility: Proper marriage or mésalliance? Population and Development Review, 19, 467–496.

    Article  Google Scholar 

  63. Retherford, R. D., & Sewell, W. H. (1989). How intelligence affects fertility. Intelligence, 13, 169–185.

    Article  Google Scholar 

  64. Rijken, A. J., & Liefbroer, A. C. (2009). Influences of the family of origin on the timing and quantum of fertility in the Netherlands. Population Studies, 63, 79–81.

    Article  Google Scholar 

  65. Rindfuss, R. R., & Bumpass, L. L. (1976). How old is too old? Age and the sociology of fertility. Family Planning Perspectives, 8, 226–230.

    Article  Google Scholar 

  66. Rindfuss, R. R., Bumpass, L. L., & St. John, C. (1980). Education and fertility: Implications for the roles women occupy. American Sociological Review, 45, 431–447.

    Article  Google Scholar 

  67. Rindfuss, R. R., Guzzo, K. B., & Morgan, S. P. (2003). The changing institutional context of low fertility. Population Research and Policy Review, 22, 411–438.

    Article  Google Scholar 

  68. Rindfuss, R. R., Morgan, S. P., & Offutt, K. (1996). Education and the Changing Age Pattern of American Fertility: 1963-89. Demography, 33, 277–290.

  69. Rodgers, J. L., Bard, D. E., & Miller, W. B. (2007). Multivariate Cholesky models of human female fertility patterns in the NLSY. Behavioral Genetics, 37, 345–361.

    Google Scholar 

  70. Rodgers, J. L., & Doughty, D. (2000). Genetic and environmental influences on fertility expectations and outcomes using NLSY kinship data. In J. L. Rodgers, D. C. Rowe, & W. B. Miller (Eds.), Genetic influences on fertility and sexuality. Theoretical and empirical contributions from the biological and behavioral sciences (pp. 85–106). Norwell, MA: Kluwer Academic.

    Google Scholar 

  71. Rodgers, J. L., Kohler, H.-P., Kyvik, O., Kirsten, K., & Christensen, K. (2001). Behavior genetic models of human fertility: Findings from a contemporary Danish twin study. Demography, 38, 29–42.

    Article  Google Scholar 

  72. Rodgers, J. L., Kohler, H.-P., McGue, M., Behrman, J. R., Petersen, I., Bingley, P., & Christensen, K. (2008). Education and cognitive ability as direct, mediating, or spurious influences on female age at first birth: Behavior genetic models fit to Danish twin data. American Journal of Sociology, 114(Suppl. 1), 202–232.

    Google Scholar 

  73. Rønsen, M. (2004). Fertility and public policies—Evidence from Norway and Finland. Demographic Research, 10(article 6), 143–170. doi:10.4054/DemRes.2004.10.6

    Article  Google Scholar 

  74. Rønsen, M., & Skrede, K. (2010). Can public policies sustain fertility in the Nordic countries? Lessons from the past and questions for the future. Demographic Research, 22(article 13), 321–346. doi:10.4054/DemRes.2010.22.13

    Article  Google Scholar 

  75. Ruokolainen, A., & Notkola, I. L. (2007). Hedelmällisyys [Fertility]. In S. Koskinen, T. Martelin, I. L. Notkola, V. Notkola, K. Pitkänen, M. Jalovaara, . . . I. Söderling (Eds.), Suomen Väestö [The population of Finland] (pp. 77–114). Helsinki, Finland: Gaudeamus Helsinki University Press.

  76. Sarna, S., Kaprio, J., Sistonen, P., & Koskenvuo, M. (1978). Diagnosis of twin zygosity by mailed questionnaire. Human Heredity, 28, 241–254.

    Article  Google Scholar 

  77. Schwartz, C. R., & Mare, R. D. (2005). Trends in educational assortative marriage from 1940 to 2003. Demography, 42, 621–646.

    Article  Google Scholar 

  78. Scott, J. (2004). Family, gender, and educational attainment in Britain: A longitudinal study. Journal of Comparative Family Studies, 35, 565–589.

    Google Scholar 

  79. Sigle-Rushton, W. (2005). Young fatherhood and subsequent disadvantage in the United Kingdom. Journal of Marriage and Family, 67, 735–753.

    Article  Google Scholar 

  80. Silventoinen, K., Krueger, R. F., Bouchard, T. J., Jr., Kaprio, J., & McGue, M. (2004). Heritability of body height and educational attainment in an international context: Comparison of adult twins in Minnesota and Finland. American Journal of Human Biology, 16, 544–555.

    Article  Google Scholar 

  81. Skirbekk, V. (2008). Fertility trends by social status. Demographic Research, 18(article 5), 145–179. doi:10.4054/DemRes.2008.18.5

    Article  Google Scholar 

  82. Skirbekk, V., Kohler, H.-P., & Prskawetz, A. (2006). The marginal effect of school leaving age on demographic events. A contribution to the discussion on causality. In S. Gustafsson & A. Kalwij (Eds.), Education and postponement of maternity. Economic analyses for industrialized countries (pp. 65–85). Dordrecht, The Netherlands: Kluwer Academic.

    Google Scholar 

  83. StataCorp. (2007). Stata statistical software: Release 10. College Station, TX: StataCorp LP.

    Google Scholar 

  84. Statistics Finland. (2007). Population structure and vital statistics by municipality 2006. Official statistics of Finland OSF. Helsinki: Statistics Finland.

  85. Tavares, L. (2010). Who delays childbearing? The relationships between fertility, education and personality traits (Dondena Working Paper 9). Milan, Italy: Dondena Center for Research on Social Dynamics.

  86. Toulemon, L., & Lapierre-Adamcyk, É. (2000). Demographic patterns of motherhood and fatherhood in France. In C. Bledsoe, S. Lerner, & J. I. Guyer (Eds.), Fertility and the male life-cycle in the era of fertility decline. International studies in demography (pp. 325–336). New York: Oxford University Press.

    Google Scholar 

  87. Trumbetta, S. L., Markowitz, E. M., & Gottesman, I. I. (2007). Marriage and genetic variation across the lifespan: Not a steady relationship? Behavioral Genetics, 37, 362–375.

    Article  Google Scholar 

  88. Udry, R. J. (1996). Biosocial models of low-fertility societies. Population and Development Review, 22(Suppl.), 325–336.

    Article  Google Scholar 

  89. Upchurch, D. M., Lillard, L. A., & Panis, C. W. (2002). Nonmarital childbearing: Influences of education, marriage and fertility. Demography, 39, 311–329.

    Article  Google Scholar 

  90. van de Kaa, D. J. (1996). Anchored narratives: The story and findings of half a century of research into the determinants of fertility. Population Studies, 50, 389–432.

    Article  Google Scholar 

  91. Vikat, A. (2004). Women’s labor force attachment and childbearing in Finland. Demographic Research, Special Collection 3(article 8), 177–212. doi:10.4054/DemRes.2004.S3.8

  92. Weeden, J., Abrams, M. J., Green, M. C., & Sabini, J. (2006). Do higher-status people really have fewer children? Education, income, and fertility in the contemporary U.S. Human Nature, 17, 377–392.

    Article  Google Scholar 

  93. Williams, R. (2000). A note on robust variance estimation for cluster-correlated data. Biometrics, 56, 645–646.

    Article  Google Scholar 

  94. Woodward, L. J., Fergusson, D. M., & Horwood, L. J. (2006). Gender differences in the transition to early parenthood. Development and Psychopathology, 18, 275–294.

    Article  Google Scholar 

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Acknowledgments

Jessica Nisén and Karri Silventoinen wish to thank Kone Foundation for support during the course of the research. Pekka Martikainen and Jaakko Kaprio were supported by the Academy of Finland (JK by Grant 141054). The authors are grateful to the editors and reviewers of Demography for their valuable comments.

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Nisén, J., Martikainen, P., Kaprio, J. et al. Educational Differences in Completed Fertility: A Behavioral Genetic Study of Finnish Male and Female Twins. Demography 50, 1399–1420 (2013). https://doi.org/10.1007/s13524-012-0186-9

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Keywords

  • Behavioral genetics
  • Childlessness
  • Completed fertility
  • Educational differences
  • Male fertility