There are two factors that have nothing to do with genetics that are more important in developing depression. One is a deficiency of omega-3 fatty acids (especially EPA). The other is inflammation induced by gut microbes that are directly transmitted to the brain via the vagus nerve to increase neuroinflammation.
In a key advance for the study of depression, a comprehensive scan of human DNA has turned up the apparent hiding places of more than a dozen genes linked to the disorder. “This is a jumping-off point” for further work to reveal the biological underpinnings of depression, which in turn can guide development of new drugs, said Ashley Winslow, an author of a paper on the work.