Partial pathogenesis is shared in substance- and nonsubstance-related addictions (e.g., pathological gambling, Internet addiction, binge-eating disorder) due to similar symptomatology and high co-morbidity. Genetics contributes to over 50% of vulnerability to substance addiction and plays a crucial role at each stage. Monoamine neurotransmitter system genes, including dopamine (DA), 5-hydroxytryptamine/serotonin (5-HT), and the endogenous opioid system, are suggested to be related to both substance and non-substance addictions. A systematic comparison of genetic mechanisms between non-substance addiction and substance addiction is necessary to reveal their essential biological similarities and differences. Thus, we conducted a review of the genetic similarities and differences between substance and non-substance addictions, aiming to enhance our understanding of addiction mechanisms and improve the clinical translation of addiction genetic findings.