Genetic variation plays a significant role in shaping complex personality traits, including impulsivity. This article explores the biological mechanisms underlying impulsivity, with a focus on dopamine and its receptor gene polymorphisms, particularly the dopamine D4 receptor (DRD4). Numerous studies have linked DRD4 polymorphisms to the impulsivity sub-trait “novelty seeking.” The review highlights recent advances in genetic research methods, approaches to measuring novelty seeking, and additional biological and environmental factors influencing this trait. Understanding the interaction between genetic variation and impulsivity provides insights into the biological basis of personality and behavior.