These are not the stories that candidates usually turn to the camera and open up about in ads.

One talked about her father’s violent temper and how she once watched him throw her mother through a plate glass door. Another recalled watching his brothers struggle to find steady work because of their criminal records. A third spoke of suffering a decade of sexual abuse as a child.

The wave of female, minority and outsider candidates that is breaking cultural barriers and toppling incumbents in the Democratic Party is also sweeping aside a longstanding norm in campaigns: That the public image of politicians — especially women — should be upbeat, uncontroversial and utterly conventional.

For many of these Democrats who were running against better-financed rivals, the breakthrough moment came after they got personal in relatively low-cost videos that went viral, reaching millions of people. Using documentary-style storytelling, which can last for several minutes, candidates have found a successful alternative to the traditional model of raising huge sums of money that get spent on expensive, 30-second television commercials.