Is Drug Addiction Genetic?

In the new Vanity Fair cover story, Robert Downey Jr. talks about his struggles with drugs and his concern that he may have passed on an addictive personality to his son (his oldest child, Indio, was arrested for cocaine possession this summer and recently entered a guilty plea). The actor's remarks raise the question: Is addiction actually genetic? To find out if you can, in fact, inherit a drug or alcohol problem, we talked to Akikur Mohamad, MD, a nationally-recognized addiction expert and founder of Inspire Malibu, a Los Angeles treatment center (which has not treated either Downey).

Robert Downey Jr. is correct: Genes play a role in addiction.

Most studies show that 50% of your risk of becoming an addict is linked to your genes, says Dr. Mohamad: "Alcohol and drug addition is a chronic brain disease and just like most chronic diseases (asthma, diabetes, etc.), there is a strong genetic component."

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A child of an addict or alcoholic is more likely to get hooked.

"Pick a dysfunction and and it's a family problem," the Iron Man star told Vanity Fair. It's not a far-fetched statement. "Sons of alcoholic fathers are up to nine times as likely to develop drinking problems as the general population," Dr. Mohamad notes. "Babies of alcoholics adopted into non-drinking homes have almost the same odds of alcoholism as they would if they'd stayed with their birth parents."

Partying as a teen can set you up for future drug problems.

Robert Downey Jr. has spoken openly about his father (director Robert Downey) introducing him to drugs at an early age, once telling People: "When my dad and I would do drugs together, it was like him trying to express his love for me in the only way he knew how." Bad idea, say the experts. "Young people (from birth to their college years) have a much higher chance of incurring permanent brain damage from using alcohol or drugs, because their brains are still developing," Dr. Mohamad explains. Not to mention, partying with the kids sends a powerful message that getting drunk or high is a smart idea.

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Nurture also matters-in a surprising way.

Nature and nurture play a role in drug abuse: "Your environment can trigger the genetic component," explains Dr. Mohamad. For an alcoholic, simply passing a bar is enough to stimulate the brain receptors that turn on a craving for alcohol. And it can be a lifelong vulnerability. "Look at Philip Seymour Hoffman," Dr. Mohamad points out. "After 20-plus years of being clean and sober, he reportedly snorted heroin several months before his death, and his addiction returned full-blown."

These two steps help prevent the problem.

"The vast majority of people who take a drink or even shoot heroin will not become addicts," says Dr. Mohamad. (Only 10% of the population has a true addiction.) But if you have a family history, it's key to make lifestyle tweaks. Two smart moves: Avoid friends who party hard and get counseling for any mental health issue that could cause you to "self medicate" with booze and pills. The encouraging news for the Downeys of the world: the cycle of addition can be broken, stresses Dr. Mohamad says: "Their fate isn't sealed."

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This article originally appeared on Health.com.