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)
