Genetic and environmental influences on early-age susceptibility and initiation of nicotine-containing product use: A twin-pairs study.

Introduction: Nicotine-containing products (NCPs) such as electronic nicotine delivery systems (ENDS) are increasingly common throughout the landscape of youth use of nicotine-containing products (NCP), and have overtaken traditional cigarette smoking modalities. This study seeks to examine the genetic and environmental influences on liability for susceptibility and initiation of ENDS and other NCPs among US children.

Methods: Data were drawn from 886 monozygotic (MZ) and dizygotic (DZ) twin pairs aged 9-10 years in the Adolescent Brain & Cognitive Development (ABCD) study at the baseline during 2016-2018. Heritability (h²) measured the proportion of the total phenotypic variation attributable to genes. Variance component models were utilized to analyze influences from the common environment (c²) and unique environmental factors (e²), taking into account correlations within twin pairs.

Results: The national sample included 50% females, 69.5% of non-Hispanic Whites, 12.8% of non-Hispanic Blacks, and 11.6% of Hispanics, with a mean age of 121.5 months. The twin sets were 60% DZ and 40% MZ. Heritability was low for NCP susceptibility (h²=0) and moderate for NCP initiation (h²=39%, p=0.02). The variance associated with NCP susceptibility was primarily influenced by environmental factors, especially one's unique factors (c²=37%, p<0.0001 vs e²=63%, p<0.0001). In contrast, the variance associated with NCP initiation was split across common and unique environmental factors (c²=32%, p=0.02 vs e²=29%, p=0.02).

Conclusions: In the era with ENDS use surging among youth, NCP initiation remains to be a heritable trait with joint influence from the environment. NCP susceptibility is largely influenced by environmental factors, especially unique environments. Continued assessment of gene × environment interaction can better inform future youth NCP interventions.