Environmental Factors in Addiction
Neuroscientists estimate that the risk of addiction for the general population is about half genetic and half environmental.
Some environmental factors have a significant impact. For example, the earlier someone starts using alcohol and/or drugs the more likely he is to become addicted: research has calculated that 50% of kids who are regular drinkers by age 14 will become alcoholics.1
In contrast, those who refrain from using drugs before age 21 have a low likelihood of addiction later in life.2 Accordingly, an environment where alcohol and/or drugs are readily available to kids at a young age increases the risk substantially.
Much of the research into genetic factors in addiction involves twin studies. These studies can shed light on hereditary influences, but because twins share genes and grow up in the same environment, it’s difficult to determine how much of the influence is genetic and how much is environmental. However, a recent study found that the risk of drug abuse is greater for adopted children (who do not share genes) if they’re raised in a dysfunctional family environment. The study’s lead author, Dr. Kenneth Kendler of the Virginia Commonwealth University, said, “For an adoptee, having a biological parent with drug abuse who did not raise you doubles your risk for drug abuse. But we also found an important role for environmental factors. If you have an adoptive sibling — with whom you have no genetic relationship — develop drug abuse, that also doubles your risk for drug abuse.” He added, “A bad environment can augment the effect of genetic risk on drug abuse.” 3
Another important environmental factor is the amount and quality of emotional and social support a person receives. Teens who reported having an adult they trusted and could talk to, for example, have a lower risk of addiction than those who don’t.4
Likewise, there’s evidence that the genetic risk for addiction can be neutralized by involved and supportive parenting.
One study involved teens who all had a particular genetic risk factor for addiction but different levels of parental support. Those who lacked involved and supportive parents had three times higher rates of drug use than those with high levels of parental support. “In families that were characterized by strong relationships between children and their parents, the effect of the genetic risk was essentially zero,” said Steven Beach, one of the researchers. “With this study and previous studies looking at environmental risk factors such as poverty, we’re finding that in many cases the best way to help children is to help families become more resilient.” Gene Brody, another researcher, added, “We found that involved and supportive parenting can completely override the effects of a genetic risk for substance abuse. It’s a very encouraging finding that shows the power of parenting.”5