Hypertrophic cardiomyopathy (HCM) is a prevalent genetic cardiovascular disease characterized by asymmetric thickening of the left ventricular wall, frequently occurring in families predisposed genetically. While HCM in twins is rare, it presents a unique opportunity to explore the disease’s genetic and epigenetic underpinnings due to the phenotypic heterogeneity observed even among genetically identical individuals. This review collates and analyzes global clinical studies that focus on the twin phenomena in HCM. It explores the genetic foundations of HCM, examines the influence of environmental and epigenetic factors on disease expression, and emphasizes the crucial role of genetic screening in the early and differential diagnosis of HCM. By focusing on twin cases in HCM, this review aims to enhance our understanding of HCM’s complex genetic background, which could lead to more personalized approaches in the management and treatment of this condition, thus drawing significant interest from researchers and clinicians alike.