RNAi can change genetically based behaviors like sex drive. (from technology review) The study used a method that overcomes two key problems of delivering RNAi directly: the difficulty of getting RNA into cells and its transitory effect. The researchers used an altered virus, which can easily infect cells but does not cause a dangerous immune response, to deliver DNA sequences from the ER-alpha gene to cells. When the gene is turned into RNA, the molecule folds in half and the two complementary sides zip together, joined by a tiny hairpin loop that's snipped by proteins in the cell, creating a short double-stranded RNA. When delivered by virus, the small hairpin RNA, or shRNA, is produced indefinitely in cells. The treatment must be delivered surgically in order to reach a precise location.