Febrile seizures (FSs) occur in children older than 1 month and without prior afebrile seizures in the absence of a central nervous system infection or acute electrolyte imbalance. Their pathogenesis is multifactorial. The most relevant familial studies evidence an occurrence rate ranging from 10% to 46% and median recurrence rate of 36% in children with positive familial history for FS. The main twin studies demonstrated a higher concordance rate in monozygotic twins with FS than in dizygotic ones. Linkage studies have proposed 11 chromosomal locations responsible to FS attributed to FEB1 to FEB11. Population-based association studies have shown at least one positive association for 14 of 41 investigated genes with FS. The proinflammatory cytokine interleukin 1β (IL-1β) was the most investigated and also gene associated with susceptibility to FS. A possible role in the overlapping of epilepsy and FS was found for 16 of 36 investigated genes. SCN1A, IL-1β, CHRNA4, and GABRG2 were the most commonly involved genes in this context. The genetic background of FS involves the regulation of different processes, including individual and familial susceptibility, modulation of immune response, and neuronal excitability and interactions with exogenous agents such as viruses.