Children’s genetics and family dynamics: An evocative effects analysis of the Norwegian Mother-Father-and-Child Study

Family demographic behavior is often studied as a response to structural conditions or parental characteristics, yet children may themselves shape key family trajectories, known as an evocative correlation. Using the Norwegian Mother, Father and Child Cohort Study (MoBa) and analyzing 40,000 genotyped mother–father–child trios, we test whether children’s polygenic indices (PGIs) predict subsequent fertility, partnership dissolution, and transition to marriage. Accounting for parental PGIs, we found limited evidence for evocative effects across most traits. The exception was that children with a higher ADHD PGI predicted increased parental partnership dissolution (7% [CI=2.9-11.8%] per s.d.), especially in families with daughters (11% [CI=4.9-18%] per s.d.), higher socioeconomic status (15% [CI=7.7-23.2%] per s.d.), and older maternal age at first birth (10% [CI=3-17%] per s.d.). The main source of variation is the socio-economic dimension where child-driven effects are stronger in higher-SES families. The study provides evidence for evocative gene-environment correlations in family demography, demonstrating the importance of child-to-parent effects in shaping family trajectories.