Genetics and vulnerability

Studies of families, twins, and adoption show that addiction risk is substantially heritable. NIDA estimates that genetic factors account for roughly 40 to 60 percent of a person's vulnerability to addiction, including the ways environment affects how genes are expressed.¹ Heritability of drug dependence is in a similar range to other chronic conditions such as type 2 diabetes and hypertension.²

There is no single "addiction gene." Many genes each contribute small effects — for example, on how a substance is metabolized, how rewarding it feels, or how a person responds to stress.

Experiences such as chronic stress, trauma, and early substance use can change how genes are switched on and off — a process called epigenetics. That means environment can amplify or soften inherited risk.

• A family history is a reason for awareness, not fear.
• Delaying or avoiding use, getting help early, and treating anxiety or depression all reduce risk.
• Many people with a strong family history never develop a disorder.
• If you are a parent in recovery, honest, age-appropriate conversations can help your children understand their own risk.