Does sibling and twin similarity in cognitive ability differ by parents' education?

Stratification scholars predominantly investigate how differences among children from different families emerge and tend to neglect differences among children from the same family. I study sibling similarity in cognitive ability and examine whether their similarity varies by parents' education. Although economic approaches and their extensions argue that disadvantaged parents reinforce differences while advantaged parents compensate for differences, I argue that parents may also make equal investments and thus accept differences among their children. I refer to the literature on stratified parenting that demonstrates that parents are engaged differently in child-rearing and their children’s skill formation processes. Because advantaged parents foster children’s talents more individually compared with disadvantaged parents, I propose that sibling similarity is lower in advantaged than in disadvantaged families. Previous studies based on sibling correlations provide conflicting evidence. To account for observable and unobservable differences among siblings, I extend the established sibling correlation approach and study dizygotic and monozygotic twins in addition to siblings. The analyses draw on novel data from a population register-based study of twin families. I find that young adult siblings and twins are less alike in cognitive ability in highly educated families than in less educated families. Hence, my results support the hypothesis concerning equal investments and indicate that stratified parenting has a long-lasting influence on children’s cognitive ability.In der Stratifizierungsliteratur wird überwiegend zur Frage geforscht, wie sich Unterschiede zwischen Kindern aus unterschiedlichen Familien erklären lassen, wobei Unterschiede, die sich zwischen Kindern aus einer Familie ergeben, unberücksichtigt bleiben. Diese Studie untersucht die Ähnlichkeit von Geschwistern in Bezug auf ihre kognitiven Fähigkeiten und fragt, ob diese in Abhängigkeit des Bildungshintergrunds variiert. Die ökonomische Literatur und Erweiterungen davon vertreten die Ansicht, dass benachteiligte Eltern Unterschiede zwischen Geschwistern verstärken, wohingegen besser gestellte Eltern Unterschiede zwischen Geschwistern eher ausgleichen. Ich dagegen argumentiere, dass Eltern auch gleiche Investitionen in ihre Kinder machen können und Unterschiede zwischen ihren Kindern akzeptieren. Ausgangspunkt hierfür ist die Literatur zu stratifizierten elterlichen Verhaltensweisen und Erziehungspraktiken, die belegt, dass Eltern ihre Kinder unterschiedlich erziehen und unterschiedlich in die Entwicklungsprozesse der Kinder eingebunden sind. Weil besser gestellte Eltern die individuellen Talente ihrer Kinder stärker fördern als benachteiligte Eltern, wird angenommen, dass sich Geschwister aus besser gestellten Familien unähnlicher sind als Geschwister von sozial benachteiligten Eltern. Bisherige Forschungsarbeiten, die die Ähnlichkeit von Geschwistern untersuchen, liefern uneinheitliche Befunde. Um beobachtbare und nicht beobachtbare Unterschiede zwischen Geschwistern berücksichtigen zu können, erweitere ich den herkömmlichen Ansatz, in dem Geschwister verglichen werden, um ein- und zweieiige Zwillinge. Die empirischen Analysen basieren auf den Daten der TwinLife Studie, einer repräsentativen Studie von Zwillingen und ihren Familien. Meine Ergebnisse zeigen, dass sich Geschwister und Zwillinge im jungen Erwachsenenalter aus bildungsnahen Familien unähnlicher sind in Bezug auf ihre kognitiven Kompetenzen im Vergleich zu Geschwistern und Zwillingen aus bildungsfernen Familien. Meine Ergebnisse unterstützen damit die Hypothese bezüglich gleicher Investitionen und deuten darauf hin, dass stratifizierte Erziehungsweisen der Eltern einen langanhaltenden Einfluss auf die Realisierung von kognitiven Fähigkeiten der Kinder haben

What have Genes got to do with it? How Social and Genetic Influences Contribute to Differences in Educational Success within the Family

Baier T. What have Genes got to do with it? How Social and Genetic Influences Contribute to Differences in Educational Success within the Family. Bielefeld: Universität Bielefeld; 2020

The Social Stratification of Environmental and Genetic Influences on Education: New Evidence Using a Register-Based Twin Sample

Baier T, Lang V. The Social Stratification of Environmental and Genetic Influences on Education: New Evidence Using a Register-Based Twin Sample. SOCIOLOGICAL SCIENCE. 2019;6:143-171.The relative importance of genes and shared environmental influences on stratification outcomes has recently received much attention in the literature. We focus on education and the gene-environmental interplay. Specifically, we investigate whether-as proposed by the Scarr-Rowe hypothesis-genetic influences are more important in advantaged families. We argue that the social stratification of family environments affects children's chances to actualize their genetic potential. We hypothesize that advantaged families provide more child-specific inputs, which enhance genetic expression, whereas the rearing environments of children in disadvantaged families are less adapted to children's individual abilities, leading to a suppression of genetic potential. We test this relationship in Germany, which represents an interesting case due to its highly selective schooling system characterized by early tracking and the broad coverage of part-time schools. We use novel data from the TwinLife panel, a population-register-based sample of twins and their families. Results of ACE-variance decompositions support the Scarr-Rowe hypothesis: Shared environmental influences on education matter only in disadvantaged families, whereas genetic influences are more important in advantaged families. Our findings support the growing literature on the importance of the gene-environmental interplay and emphasize the role of the family environment as a trigger of differential genetic expression

Socioeconomic Background and Gene-Environment Interplay in Social Stratification across the Early Life Course

To what extent are differences in education, occupational standing, and income attributable to genes, and do genetic influences differ by parents' socioeconomic standing? When in a children's life course does parents' socioeconomic standing matter for genetic influences, and for which of the outcomes, fixed at the different stages of the attainment process, do they matter most? We studied these research questions using Finnish register-based data on 6,529 pairs of twins born between 1975 and 1986. We applied genetically sensitive variance decompositions and took gene-environment interactions into account. Since zygosity was unknown, we compared same-sex and opposite-sex twins to estimate the proportion of genetic variation. Genetic influences were strongest in education and weakest in income, and always strongest among those with the most advantaged socioeconomic background, independent of the socioeconomic indicator used. We found that the shared environment influences were negligible for all outcomes. Parental social background measured early during childhood was associated with weaker interactions with genetic influences. Genetic influences on children's occupation were largely mediated through their education, whereas for genetic influences on income, mediation through education and occupational standing made little difference. Interestingly, we found that non-shared environment influences were greater among the advantaged families and that this pattern was consistent across outcomes. Stratification scholars should therefore emphasize the importance of the non-shared environment as one of the drivers of the intergenerational transmission of social inequalities.Peer reviewe

Socioeconomic Background and Gene-Environment Interplay in Social Stratification across the Early Life Course

To what extent are differences in education, occupational standing, and income attributable to genes, and do genetic influences differ by parents’ socioeconomic standing? When in a children’s life course does parents’ socioeconomic standing matter for genetic influences, and for which of the outcomes, fixed at the different stages of the attainment process, do they matter most? We studied these research questions using Finnish register-based data on 6,529 pairs of twins born between 1975 and 1986. We applied genetically sensitive variance decompositions and took gene-environment interactions into account. Since zygosity was unknown, we compared same-sex and opposite-sex twins to estimate the proportion of genetic variation. Genetic influences were strongest in education and weakest in income, and always strongest among those with the most advantaged socio-economic background, independent of the socioeconomic indicator used. We found that the shared environment influences were negligible for all outcomes. Parental social background measured early during childhood was associated with weaker interactions with genetic influences. Genetic influences on children’s occupation were largely mediated through their education, whereas for genetic influences on income, mediation through education and occupational standing made little difference. Interestingly, we found that non-shared environment influences were greater among the advantaged families and that this pattern was consistent across outcomes. Stratification scholars should therefore emphasize the importance of the non-shared environment as one of the drivers of the intergenerational transmission of social inequalities.  (Repository for the codes used: https://github.com/INVEST-flagship/Erola-et-al-2021-Socioeconomic-Background-and-Gene-Environment-Interplay-in-Social-Stratification)</p

Socioeconomic background and gene-environment interplay in social stratification across the early life course

To what extent are genetic effects on children’s education, occupational standing, and income shaped by their parents’ socioeconomic characteristics? Does the impact vary over their children’s early life course, and are there differences across the social strata? We studied these research questions with Finnish register-based data on 6,542 pairs of twins born from 1975 to 1986. We applied the classical twin design to estimate the relative importance of genes. As outcomes, we compared education, occupation, and income in early adulthood. We found that shared environment influences were negligible in all cases. Notably, the proportion of genetic effects explained by parental characteristics mattered most for education and for occupation only because they were associated with their children’s education—but not for income. We did not find any variation across their early life course; however, we found that genetic influences were stronger among the advantaged families for income and education. Thus, gene-environment interactions (GxE) operate differently for different status-related characteristics. For the unique environment, the pattern was consistent across outcomes as the effect was greater among the advantaged families. Stratification scholars should therefore emphasize the importance of the unique environment as one of the drivers of the intergenerational transmission of social inequalities.</p

Genetic Influences on Educational Achievement in Cross-National Perspective

There is a growing interest in how social conditions moderate genetic influences on education [gene–environment interactions (GxE)]. Previous research has focused on the family, specifically parents’ social background, and has neglected the institutional environment. To assess the impact of macro-level influences, we compare genetic influences on educational achievement and their social stratification across Germany, Norway, Sweden, and the United States. We combine well-established GxE-conceptualizations with the comparative stratification literature and propose that educational systems and welfare-state regimes affect the realization of genetic potential. We analyse population-representative survey data on twins (Germany and the United States) and twin registers (Norway and Sweden), and estimate genetically sensitive variance decomposition models. Our comparative design yields three main findings. First, Germany stands out with comparatively weak genetic influences on educational achievement suggesting that early tracking limits the realization thereof. Second, in the United States genetic influences are comparatively strong and similar in size compared to the Nordic countries. Third, in Sweden genetic influences are stronger among disadvantaged families supporting the expectation that challenging and uncertain circumstances promote genetic expression. This ideosyncratic finding must be related to features of Swedish social institutions or welfare-state arrangements that are not found in otherwise similar countries

A longitudinal twin family study of the life course and individual development (TWINLIFE): Data collection and instruments of wave 1 face-to-face interviews

Brix J, Pupeter M, Rysina A, et al. A longitudinal twin family study of the life course and individual development (TWINLIFE): Data collection and instruments of wave 1 face-to-face interviews. TwinLife Technical Report Series. Vol 05. Bielefeld: Project TwinLife "Genetic and social causes of life chances" (Universität Bielefeld / Universität des Saarlandes); 2017

Gebühren mindern Studierneigung nicht

Helbig M, Baier T. Gebühren mindern Studierneigung nicht. WZ-Brief Bildung. 2011;18

War all die Aufregung umsonst? Über die Auswirkung der Einführung von Studiengebühren auf die Studienbereitschaft in Deutschland.

Baier T, Marcel H. War all die Aufregung umsonst? Über die Auswirkung der Einführung von Studiengebühren auf die Studienbereitschaft in Deutschland. Berlin: WZB Discussion paper 2011-002; 2011