Genetic factors contribute approximately what portion of addiction risk?

• A. One Quarter
• B. One Half
• C. Three Quarters
• D. All of the Above

Answer: (B)

Genetic factors account for about half of addiction risk. Research, especially twin studies, shows that there’s a substantial genetic contribution to who develops addictive disorders, with heritability estimates commonly around 40–60%, averaging near 50%. That means roughly half of the variability in risk comes from genetic differences, while the other half comes from environmental influences and how genes interact with those environments. Addiction is polygenic, so many genes contribute small effects, and environment such as exposure, stress, social context, and support all shape whether risk translates into actual addiction. The other options understate or overstate the genetic contribution, and the idea that all of the above applies isn’t consistent with the typical range of heritability estimates.