Direct and Indirect Genetic Effects on Aggression

Camiel M van der Laan; Steve G A van de Weijer; René Pool; Jouke-Jan Hottenga; Toos C E M van Beijsterveldt; Gonneke Willemsen; Meike Bartels; Michel G Nivard; Dorret I Boomsma

doi:10.1016/j.bpsgos.2023.04.006

Direct and Indirect Genetic Effects on Aggression

Biol Psychiatry Glob Open Sci. 2023 Apr 29;3(4):958-968. doi: 10.1016/j.bpsgos.2023.04.006. eCollection 2023 Oct.

Authors

Camiel M van der Laan^{1

2}, Steve G A van de Weijer², René Pool¹, Jouke-Jan Hottenga¹, Toos C E M van Beijsterveldt¹, Gonneke Willemsen¹, Meike Bartels¹, Michel G Nivard¹, Dorret I Boomsma¹

Affiliations

¹ Department of Biological Psychology, Vrije Universiteit, Amsterdam, the Netherlands.
² Netherlands Institute for the Study of Crime and Law Enforcement, Amsterdam, the Netherlands.

Abstract

Background: Family members resemble each other in their propensity for aggression. In twin studies, approximately 50% of the variance in aggression can be explained by genetic influences. However, if there are genotype-environment correlation mechanisms, such as environmental manifestations of parental and sibling genotypes, genetic influences may partly reflect environmental influences. In this study, we investigated the importance of indirect polygenic score (PGS) effects on aggression.

Methods: We modeled the effect of PGSs based on 3 genome-wide association studies: early-life aggression, educational attainment, and attention-deficit/hyperactivity disorder (ADHD). The associations with aggression were tested in a within- and between-family design (37,796 measures from 7740 individuals, ages 3-86 years [mean = 14.20 years, SE = 12.03], from 3107 families, 55% female) and in a transmitted/nontransmitted PGS design (42,649 measures from 6653 individuals, ages 3-61 years [mean = 11.81 years, SE = 8.68], from 3024 families, 55% female). All participants are enrolled in the Netherlands Twin Register.

Results: We found no evidence for contributions of indirect PGS effects on aggression in either a within- and between-family design or a transmitted/nontransmitted PGS design. Results indicate significant direct effects on aggression for the PGSs based on early-life aggression, educational attainment, and ADHD, although explained variance was low (within- and between-family: early-life aggression R² = 0.3%, early-life ADHD R² = 0.6%, educational attainment R² = 0.7%; transmitted/nontransmitted PGSs: early-life aggression R² = 0.2%, early-life ADHD R² = 0.9%, educational attainment R² = 0.5%).

Conclusions: PGSs included in the current study had a direct (but no indirect) effect on aggression, consistent with results of previous twin and family studies. Further research involving other PGSs for aggression and related phenotypes is needed to determine whether this conclusion generalizes to overall genetic influences on aggression.

Keywords: Aggression; Genetic nurture; Indirect genetic effects; Polygenic score; Transmitted/nontransmitted alleles; Within-family.

Abstract

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