Identifying intergenerational influences of smoking, alcohol, and wider risk behaviours on education via molecular genetics.

Abstract

Background: This thesis investigates the intergenerational transmission of smoking, alcohol
consumption, and wider risk behaviours, and their impact on educational achievement. The
primary objective is to explore the causal directionality of these associations using molecular
genetic methods. Although evidence links parental and child risk behaviours with lower
educational achievement, environmental and genetic confounding complicates the
establishment of causal pathways.
Methods: Using family-based data from two large cohort studies, the UK’s Avon Longitudinal
Study of Parents and Children (ALSPAC) and Norway’s Mother, Father, and Child Cohort study
(MoBa), this research triangulates findings by employing both phenotypic and genetic
within-family approaches. Molecular genetics methods, including within-family Mendelian
randomization, bidirectional MR, and GREML are used to assess the influence of parental
and adolescent behaviours on educational achievement.
Results: Bidirectional Mendelian randomization analyses reveal that educational
achievement has a casual influence on adolescent risk behaviour, but not vice versa.
Heritability analyses reveal significant genetic overlap between these traits. Furthermore,
when examining specific behaviours, I find that parental alcohol consumption has no strong
causal effects on children’s education, while maternal smoking shows a modest negative
association with children’s educational achievement, though genetic confounding is present.
Conclusions: The findings contribute to a more nuanced understanding of the mechanisms
underlying these relationships, providing robust evidence of how genetic predispositions
and environmental exposures intersect to shape educational outcomes. This research
suggests that educational achievement, or traits closely related to, may influence
engagement in smoking, alcohol consumption and wider risk behaviours. While the genetic
evidence supports support these relationships, further research would be needed to
determine whether educational interventions could effectively target these pathways. These
findings contribute to understanding how these behaviours interact with education,
informing future education and public health policy.

Date of Award	30 Sept 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	Neil Davies (Supervisor), George Davey Smith (Supervisor), Alexandra Havdahl (Supervisor), Amanda M M Hughes (Supervisor) & Tim T Morris (Supervisor)