Determining the cause of mental illness is like figuring out what makes good art. In each case, the answer is no.
Great art requires both innate talent and the right tools.
In a similar way, miswired minds result from the wrong mix of nature and nurture. As with many diseases, mental illness can run in families, suggesting that genetics plays a role. But genes don't tell the whole story. Influences other than genes probably are the reason. They aren't always available for scientific data-gathering.