As they add to the bios for the slain at VT, I take note of something, almost by default. It catches my eye when they say that a dead student was an only child. I think the media knows how that strikes the heart even harder. They rarely say s/he was one of three (except to say something more extreme, like 9th of 10), but they point out the only child status. At least three were only children. One other was the only born just after the death of a sibling.
When I consider that most only children were not created that way by choice, I wonder the additional pain these parents feel, magnified by the old wounds of infertility. Their biggest fear, or at least mine, is that their only is no longer. There is neither an heir nor a spare. Only gets even lonelier.
I periodically tell my son that he needs to outlive me.