Genetics, environment, and smoking in pregnancy

A study in the January issue of Developmental Psychology examined the long-term effect of prenatal exposure to tobacco. This project was unique in that the researchers also considered the expression of genes affecting the dopamine (a neurotransmitter) system in the brain. The researchers asked preschoolers to complete a task that required "executive control;" the executive functions are skills required for goal-directed behaviour, including self-monitoring, inhibiting inappropriate behaviour, and shifting from one task or problem-solving strategy to another. They found that kids with one expression of gene (the genotype; a TaqIA allele was looked at, in case you're interested) had more trouble than those with another genotype on the executive control task. Kids with the allele who were also exposed to tobacco prenatally had the most trouble of any group on the activity.

The researchers concluded that genes have an effect on behaviour, but their impact is in turn affected by environmental factors as well. It's not genes OR environment that is important, it's both. Psychologists have talked about the gene X environment interaction since before I went to school, with some suggesting a "diathesis-stress" model for a number of psychological conditions. That is, genetics might predispose someone to be at a higher risk for certain kinds of difficulties, but the environmental factors have an impact on the eventual outcomes.

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