That's from Six Feet Under, no? There's some good poetic value in it, but I don't know if it's actually true. It has more to do with the effect it has for some

That's from Six Feet Under, no? There's some good poetic value in it, but I don't know if it's actually true. It has more to do with the effect it has for someone's "normal" life cycle, which is why orphan is only applied to children and not adults. And as the sibling comment mentions, it was pretty common in a family of ~5-10 to have at least one child die.