Chiari malformations are considered to have a multifactorial etiology, likely influenced by environmental and genetic factors. This chapter will detail the evidence that supports a genetic contribution to the disorder, including discussions of twin studies, familial aggregation, co-occurrence with known genetic syndromes, and previous genetic studies. While no susceptibility genes have been identified to date, gene identification efforts are continuing. It is expected that researchers will have a more complete understanding of the specific genes and biological pathways that contribute to disease development in the coming years. The future benefits from genetic research of Chiari I and II may include the development of genetic tests that result in more accurate and faster diagnoses as well as new targeted treatment options for patients.