Evidence for Genetic Nurture Effects on Substance Use

Area of Science:

• Behavioral Genetics
• Psychiatric Genetics
• Substance Use Research

Background:

• Substance use disorders (SUDs) exhibit familial aggregation.
• Genetic nurture, the influence of parental genetics on offspring via the environment, is a key factor beyond direct genetic transmission.
• Understanding genetic nurture's role in SUDs is crucial for developing targeted interventions.

Purpose of the Study:

• To investigate the impact of genetic nurture on tobacco, alcohol, and cannabis use.
• To differentiate genetic nurture effects from direct genetic transmission.
• To explore stage-specific and parent-specific effects of genetic nurture on substance use behaviors.

Main Methods:

• Utilized transmitted and non-transmitted polygenic scores in up to 15,863 adults from the Lifelines cohort with at least one genotyped parent.
• Assessed genetic nurture effects on smoking quantity (cigarettes per day, pack-years), and initiation of tobacco, alcohol, and cannabis use.
• Conducted mediation analyses to identify pathways through which parental smoking influences offspring substance use.

Main Results:

• Genetic nurture significantly influenced smoking quantity (cigarettes per day: β=0.03; pack-years: β=0.02), explaining 18.8% and 28.6% of genetic transmission effects, respectively.
• Genetic nurture had minimal impact on tobacco or cannabis initiation, indicating stage-specific effects.
• Maternal and paternal genetic nurture contributed equally to offspring smoking quantity, with maternal smoking showing higher mediation proportions.

Conclusions:

• Genetic nurture plays a significant role in the quantity of smoking, but not initiation, suggesting stage-specific influences.
• Both parents contribute equally to genetic nurture effects on smoking quantity, with parental smoking mediating these effects.
• Future research and interventions should consider stage-specific and parent-specific genetic nurture effects in substance use.