Affiliation:
1. Radboud University Nijmegen, Behavioural Science Institute, the Netherlands
2. Department of Biological Psychology, Vrije Universiteit Amsterdam, the Netherlands
3. Avera Institute for Human Genetics, Sioux Falls, SD
Abstract
Abstract
Introduction
Classical twin studies show that smoking is heritable. To determine if shared family environment plays a role in addition to genetic factors, and if they interact (G×E), we use a children-of-twins design. In a second sample, we measure genetic influence with polygenic risk scores (PRS) and environmental influence with a question on exposure to smoking during childhood.
Methods
Data on smoking initiation were available for 723 children of 712 twins from the Netherlands Twin Register (64.9% female, median birth year 1985). Children were grouped in ascending order of risk, based on smoking status and zygosity of their twin-parent and his/her co-twin: never smoking twin-parent with a never smoking co-twin; never smoking twin-parent with a smoking dizygotic co-twin; never smoking twin-parent with a smoking monozygotic co-twin; and smoking twin-parent with a smoking or never smoking co-twin. For 4072 participants from the Netherlands Twin Register (67.3% female, median birth year 1973), PRS for smoking were computed and smoking initiation, smoking heaviness, and exposure to smoking during childhood were available.
Results
Patterns of smoking initiation in the four group children-of-twins design suggested shared familial influences in addition to genetic factors. PRS for ever smoking were associated with smoking initiation in all individuals. PRS for smoking heaviness were associated with smoking heaviness in individuals exposed to smoking during childhood, but not in non-exposed individuals.
Conclusions
Shared family environment influences smoking, over and above genetic factors. Genetic risk of smoking heaviness was only important for individuals exposed to smoking during childhood, versus those not exposed (G×E).
Implications
This study adds to the very few existing children-of-twins (CoT) studies on smoking and combines a CoT design with a second research design that utilizes polygenic risk scores and data on exposure to smoking during childhood. The results show that shared family environment affects smoking behavior over and above genetic factors. There was also evidence for gene–environment interaction (G×E) such that genetic risk of heavy versus light smoking was only important for individuals who were also exposed to (second-hand) smoking during childhood. Together, these findings give additional incentive to recommending parents not to expose their children to cigarette smoking.
Funder
European Research Council
Netherlands Organization for Scientific Research (NWO)
Genetic and Family Influences on Adolescent Psychopathology and Wellness
A twin-sib study of adolescent wellness
Dutch Ministry of Education, Culture and Science and the Netherlands Organization for Scientific Research
VU University’s Institute for Health and Care Research (EMGO+)
Neuroscience Campus Amsterdam (NCA)
Biomolecular Resources Research Infrastructure
Foundation for the National Institutes of Health
Rutgers University Cell and DNA Repository
Avera Institute, Sioux Falls, South Dakota (USA)
National Institutes of Health
Brain & Behavior Research Foundation
Publisher
Oxford University Press (OUP)
Subject
Public Health, Environmental and Occupational Health