Consanguineous marriage is defined as a marriage between a male and female within the same family lineage, not exceeding three generations. Such marriages facilitate the development and manifestation of a range of hereditary diseases caused by recessive genes on chromosomes, which can become apparent in subsequent generations. In Vietnam, consanguineous marriages remain common, particularly among ethnic minorities. Fortunately, Vietnam has collected resident data on 104 million citizens, which has been utilized for economic and social development purposes. This study aims to propose tools for preventing consanguineous marriages by checking whether two individuals planning to marry are related within three generations before registering their marriage, using the Vietnam’s National Resident Database. The study proposes three methods based on three different data structures (simple graph, AVL tree, and hash table). Theoretical and experimental analyses demonstrate that the method based on the hash table provides the fastest verification of whether two individuals planning to marry are related within three generations, outperforming the current methods.