Some psychologists believe that exposure to violence and abuse is especially traumatizing for “home-grown” kids who have never seen or experienced anything like this. It does not mean that such children should be forced to watch shocking content or horror movies to develop tolerance.
There is one chance in a million that a kind child brought up to disdain violence will turn out to be a Batman upon facing atrocities (in all honesty, Batman himself had a psychological trauma).
The point is that the policy of complete prohibition and tabooing of such things only leads to the inevitable build-up of unhealthy interest in them. We recommend the Hoverwatch service that will help you understand what content your children consume on their devices and take preventive action, if necessary.