Other people's dead kids. They never think it will happen to their kids because they're kept safe by daddy's hero fantasies or robotic devotion to statistics.
Of course, it does happen to their kids.
Occasionally it happens to their kids because they indiscriminately arm the far-right, who then get upset nobody will give them hand jobs, so decide to indiscriminately fire in to crowds of people.
But mostly it happens because their children kill themselves with daddy's guns, that they were probably taught at an early age how to load and fire because that's what "responsible gun owners" crow about doing.