Pulmonary arterial hypertension (PAH) remains a vexing clinical disease with no cure. Despite advances and the discovery of a gene (BMPR2) associated with many of the hereditary forms of the disease, and some cases not previously known to be inherited, the reasons for mutations in this gene as a cause remain somewhat elusive. Clearly, a complex interplay exists between genetic alterations, environmental exposures (including infections), and disease development. This article addresses the advances in the genetics of PAH, including the identification of genetic etiologies and modulators, and the role of genetics in predicting disease progression and targeting therapeutics.