Answer: The drug abuse is influenced by the environment and exerts influence on the gene expressions.
Step-by-step explanation:
The genetic make up of the person is decides, which genes will be expressed and develop a trait in an individual. But this genetic expression can be influenced by the environmental factors like food, exposure to sunlight, and others. This study which relate environment with the genetic make up is called epigenetics. No person is drug addict by birth but the consumption of drug can influence the genetic make up and traits in a abuser. So here, the environment is influencing the genetic basis of a abuser.