Eh, I mean personally I would find that less than ideal, as far as motivation for a character? To just handwave it away, as an excuse for her violence, and then expect me to empathize with her without any real investment in her BEFORE she became a violent woman. Well, I mean basically that sounds like the amount of backstory and time they gave MahMah from the Dredd film in 2012. "She was abused, and became homicidal, the end." And...well she wasn't the protagonist of that storyAnd honestly, if you haven't seen the film, her "backstory" is pretty much glossed over to establish she has anger issues and get to what's meant to be the meat of the movie. It's not like the writer/director spent a substantial part of the film establishing her traumatic upbringing; they pretty much show it for a couple of minutes just to show her anger issues have been around since her childhood. And so we're clear, its supposedly a medical disorder, not one born of an unhappy childhood; that's how quickly they wanted to get the story going.