According to carrierclinic: Chemical Dependency is characterized by the repeated, uncontrollable use of alcohol and/or drugs in a way that threatens the individual's physical and mental health and well-being as well as the physical safety and emotional well-being of those around him or her.
So I would say a few factors that contribute to Chemical Dependency are: Genetics, Mental Illnesses, Possibly Home & School Environment, Stress, Trauma/Abuse and much more..
I really hope my answer helps!
