Interplay between heritability of smoking and environmental conditions? A comparison of two birth cohorts

BACKGROUND: Attitudes and policy towards smoking changed over the past years in many countries including the Netherlands. Generally, this led to a decrease in smoking prevalence. As demonstrated in twin and family studies, individual differences in smoking behavior are partly influenced by genetic factors. We explore whether the current change in environmental conditions has influenced the genetic architecture of smoking. This would constitute evidence for Gene × Environment (G×E) interaction. METHODS: Data on smoking were available from 2 cohorts of young adult twins (18-25 year) registered with the Netherlands Twin Register. The first cohort completed a survey in 1993-1995 (n = 2669) and the second in 2009-2010 (n = 2339). Prevalence and genetic architecture of smoking were compared across cohorts using structural equation models in MX. RESULTS: Smoking prevalence decreased from 40-51% to 22-23% between 1993-1995 and 2009-2010. Genetic analyses, making use of the different genetic resemblance in monozygotic and dizygotic twins, showed that the heritability was the same in both cohorts. CONCLUSIONS: The change in policy and smoking attitudes that led to a decrease in prevalence of smoking did not change the heritability of smoking and thus no evidence was found for GxE interaction.