At the Mercy of our Environment: Epigenetic Influences Have Complex Impact

Last week I attended a talk by Dr. Valerie Knopik, a genetic biologist, entitled "Genes + Environment = behavior?" The concept of nature and nurture both coming together to affect our biology and behavior is nothing new, but Knopik challenged the assumption that some sort of linear model could sufficiently describe the relationship.  Rather than genes and environment each contributing separately to our behavior, she eloquently displayed the complex web of factors relating the two.  Not only do nature and nurture influence us, but they also influence each other in complex ways, sometimes even before they affect us.  What does this mean for international health?  I feel we often talk about how cultural, political, historic, and geographic factors have effects on people's health to no fault of their own, and that not everyone has equal access to health.  However, Knopik's talk shows how this can go beyond social factors to influence our actual biology in serious and lasting ways.

Dr. Knopik discussed her work with smoking during pregnancy (SDP) and how that relates to ADHD in children.  First she described some of the variables that can predict for smoking during pregnancy, most notable of which is, as could be expected, chronic smoking abuse.  However, this behavior is also linked to a variety of other circumstances, such as social phobia and depression, and church attendance actually had a protective effect against it.  Ultimately this research into related variables to smoking during pregnancy found that this behavior was also a proxy for other behaviors, and that it was also genetically influenced.  When we turn our attention to children who faced SDP in utero, children are at highest risk for developing ADHD when they have genetically inherited the risky allele for the nicotinic receptor AND are exposed to SDP.  If the children ONLY have the risky allele OR are exposed to SDP, but not both, risk of ADHD is much lower.  

This information has obvious application in the field of public health, and international health.  When we seek to promote healthy behavior change, or even just to understand the root causes of a health problem in a given community, it is vital to remember that there is more at play than the choices people make.  I think it is quite common for public health professionals to understand that environmental limitations such as socioeconomic status and education can negatively impact health behaviors, but biology must not be counted out.  The unfortunate thing is that this can be hard to change; as epigenetics research shows, we are not entirely in control of our gene expression but are at the mercy of environmental exposure, prenatal care, and even behavior of the generations that came before us.  Ideally, we need to be able to communicate to people that their behaviors are not only affecting them but also their descendants for generations to come.  More realistically, we can recognize that genetics and environment do not only independently impact our health but also influence each other, so any particular health concern we seek to attend to as international health officials requires careful analysis and deep understanding of all contributing factors.