Periodic Reporting for period 4 - CAPE (Ghosts from the past: Consequences of Adolescent Peer Experiences across social contexts and generations)
Reporting period: 2022-08-01 to 2023-07-31
Multiple studies have described long-term negative consequences when adolescents’ peer relationships are dysfunctional but so far, this research has focused on psychological and behavioral development, neglecting findings from attachment and social learning theory and research that interpersonal experiences can be transmitted across social contexts and across generations. In detail, we know that adolescent peer experiences are central to romantic development through providing opportunities to meet dating partners and by enabling young people to develop the skills that are needed to navigate romantic relationships.
However, studies thus far rarely covered adulthood and it is not clear how adolescents’ peer experiences affect later life although it is highly likely that adolescent peer experiences are important precursors of adult friendships. Moreover, traits, behaviors, and relationship experiences are partially passed on from one generation to the next. It may well be that young people’s peer experiences also have their origins in the developmental histories of their parents. This assumption challenges our current understanding of social development and necessitates that the study of antecedents of specific peer experiences needs to go much further back in time and should zoom in on the pathways that carry this transmission. If intergenerational continuity in specific peer experiences is detected, we need to elucidate whether environmental or genetic mechanisms drive this transmission.
In CAPE, we tackled these research gaps by applying theoretical assumptions and empirical findings from other fields to the study of peer relationships and their consequences across contexts and generations. Parenting and other correlates of adolescent peer experiences were studied systematically, and we extended a multiple generation study to explore whether interpersonal experiences prior to conception of own offspring affected offspring social development via parenting. In most analyses, we took a genetically informed approach, that is, controlled for genetic mediation in regression analyses. In doing so, we utilized and contributed to data from TRAILS (www.trails.nl/eng) which has been following over 2000 individuals from age 11 und their early thirties. Over the years, TRAILS participants and their parents have reported 8 times on a multitude of psychological, social, and behavioral development aspects and many provided biological material for genetic analyses. Many TRAILS participants have started families of their own by now, which allows for unique multiple generation family study. As part of CAPE, the TRAILS NEXT sample of participants with children was extended into middle childhood and we collected data on relationship quality, parenting, parental experiences more generally. We collected biosamples for DNA extraction from both parents and the offspring and interviewed offspring as well as carried out various tests. Results have been published in various articles.
However, studies thus far rarely covered adulthood and it is not clear how adolescents’ peer experiences affect later life although it is highly likely that adolescent peer experiences are important precursors of adult friendships. Moreover, traits, behaviors, and relationship experiences are partially passed on from one generation to the next. It may well be that young people’s peer experiences also have their origins in the developmental histories of their parents. This assumption challenges our current understanding of social development and necessitates that the study of antecedents of specific peer experiences needs to go much further back in time and should zoom in on the pathways that carry this transmission. If intergenerational continuity in specific peer experiences is detected, we need to elucidate whether environmental or genetic mechanisms drive this transmission.
In CAPE, we tackled these research gaps by applying theoretical assumptions and empirical findings from other fields to the study of peer relationships and their consequences across contexts and generations. Parenting and other correlates of adolescent peer experiences were studied systematically, and we extended a multiple generation study to explore whether interpersonal experiences prior to conception of own offspring affected offspring social development via parenting. In most analyses, we took a genetically informed approach, that is, controlled for genetic mediation in regression analyses. In doing so, we utilized and contributed to data from TRAILS (www.trails.nl/eng) which has been following over 2000 individuals from age 11 und their early thirties. Over the years, TRAILS participants and their parents have reported 8 times on a multitude of psychological, social, and behavioral development aspects and many provided biological material for genetic analyses. Many TRAILS participants have started families of their own by now, which allows for unique multiple generation family study. As part of CAPE, the TRAILS NEXT sample of participants with children was extended into middle childhood and we collected data on relationship quality, parenting, parental experiences more generally. We collected biosamples for DNA extraction from both parents and the offspring and interviewed offspring as well as carried out various tests. Results have been published in various articles.
Across the five years of CAPE, we have accomplished a lot of activities, including in terms of data collection or making ready for use:
- qualitative interviews about memories of interpersonal relationships and how they affect adult interpersonal functioning (not published yet)
- analyses of existing data on intergenerational transmission of peer experiences
- initiation of data collection in TRAILS NEXT, covering experiments, interviews with children, observations, interviews and questionnaires - approximately 150 families have participated in the home visit set up as part of CAPE (described in Hartman et al., 2022)
- we were able to genotype parents of initial TRAILS participants, resulting in dataset of over 700 trio's (see Kretschmer et al., 2022 JCPP). Genetic trio data in combination with detailed phenotypic information is rare
Next to this, we have established close collaboration with Australian team of Australian Temperament Project, which is comparable to TRAILS and TRAILS NEXT, allowing for mutual replication of results. This has led to a shared grant proposal, shared PhD, and prospective collaboration plans. We have also established collaboration with individual researchers, including at University of Quebec, University of Edinburgh, University College London, and Birkbeck University, as well as presented findings in various invited talks (e.g. Center for Research in Economics and Statistics, Paris in 2021, Summer Institute of the Joint Institute for Individualization in a Changing Environment, Münster in 2022 and the Sociogenomics conference in Helsinki in 2023).
Take-home messages from this project, that were not studied at all or without using rigorous methods include:
1. Evidence for an effect of adolescent interpersonal experiences on parenting is not universal and likely runs via psychological health. This means that negative peer experiences might affect psychological health, which in turn affects parenting.
2. There is support for intergenerational transmission of bullying perpetration, that is, children whose parents bullied others are also more likely to aggress against peers (Wiertsema et al., 2022)
3. Bullies are rewarded with higher status but are not liked by others (Wiertsema et al. 2023)
4. Bullies are at greater risk for substance use later on (Vrijen et al., 2021)
5. Evolutionary theories have assigned bullying perpetration and advntage but there is only limited evidence when looking longitudinally (Kretschmer et al., 2022)
6. Genes might explain any association between problematic peer experiences and later psychological outcomes (Vrijen et al., 2023)
- qualitative interviews about memories of interpersonal relationships and how they affect adult interpersonal functioning (not published yet)
- analyses of existing data on intergenerational transmission of peer experiences
- initiation of data collection in TRAILS NEXT, covering experiments, interviews with children, observations, interviews and questionnaires - approximately 150 families have participated in the home visit set up as part of CAPE (described in Hartman et al., 2022)
- we were able to genotype parents of initial TRAILS participants, resulting in dataset of over 700 trio's (see Kretschmer et al., 2022 JCPP). Genetic trio data in combination with detailed phenotypic information is rare
Next to this, we have established close collaboration with Australian team of Australian Temperament Project, which is comparable to TRAILS and TRAILS NEXT, allowing for mutual replication of results. This has led to a shared grant proposal, shared PhD, and prospective collaboration plans. We have also established collaboration with individual researchers, including at University of Quebec, University of Edinburgh, University College London, and Birkbeck University, as well as presented findings in various invited talks (e.g. Center for Research in Economics and Statistics, Paris in 2021, Summer Institute of the Joint Institute for Individualization in a Changing Environment, Münster in 2022 and the Sociogenomics conference in Helsinki in 2023).
Take-home messages from this project, that were not studied at all or without using rigorous methods include:
1. Evidence for an effect of adolescent interpersonal experiences on parenting is not universal and likely runs via psychological health. This means that negative peer experiences might affect psychological health, which in turn affects parenting.
2. There is support for intergenerational transmission of bullying perpetration, that is, children whose parents bullied others are also more likely to aggress against peers (Wiertsema et al., 2022)
3. Bullies are rewarded with higher status but are not liked by others (Wiertsema et al. 2023)
4. Bullies are at greater risk for substance use later on (Vrijen et al., 2021)
5. Evolutionary theories have assigned bullying perpetration and advntage but there is only limited evidence when looking longitudinally (Kretschmer et al., 2022)
6. Genes might explain any association between problematic peer experiences and later psychological outcomes (Vrijen et al., 2023)
CAPE has clarified that social development is complex and that linear effects from peer relationships to parenting are likely not present universally, interrupting what we thought would be a clear intergenerational transmission mechanism. Moreover, genes might explain any overlap. These conclusions are sobering but highlight the absolute importance of rigorous methods, including longterm longitudinal and multiple-generation studies (see also Kretschmer CDP 2021) and genetic information. We have been able to contribute to improve resources and knowledge for future researchers by adding to the TRAILS NEXT cohort and by genotyping parent of TRAILS participants. Furthermore, the group is now recognized in terms of its work on intergenerational genetically-informed research on social development, as evidenced, for instance, in invitations to join consortia, give talks, contribute to special issues, host sabbaticals and workshops.
Exemplary, the novel of integrating genetic information into social development research, underlines the progress of the project beyond the state of the art: In 2016, when the project was developed, polygenic indices were only at the brink of development, yet we were able to quickly take-up this completely new approach and have published several papers using it (e.g. Kretschmer et al., 2023 ECAP, Kretschmer et al., 2022 JCP, Vrijen et al., DP 2023). As a second example, CAPE has introduced and tested the idea that preconception factor can have a long reach - something that in 2016 was not discussed widely in psychology. Now, the role of adolescence as shaping future development and, in doing so, also that of an offspring, is recognized and tested in different labs around the world.
Exemplary, the novel of integrating genetic information into social development research, underlines the progress of the project beyond the state of the art: In 2016, when the project was developed, polygenic indices were only at the brink of development, yet we were able to quickly take-up this completely new approach and have published several papers using it (e.g. Kretschmer et al., 2023 ECAP, Kretschmer et al., 2022 JCP, Vrijen et al., DP 2023). As a second example, CAPE has introduced and tested the idea that preconception factor can have a long reach - something that in 2016 was not discussed widely in psychology. Now, the role of adolescence as shaping future development and, in doing so, also that of an offspring, is recognized and tested in different labs around the world.