What parent hasn't said that to a child. Or at least thought it.
"You're taking years off my life," we say. And maybe we mean it and maybe we don't, but it seems like all that energy we are investing in our offspring must come from somewhere.
Scientists talk about the "disposable soma" theory. (Soma refers to an organism's body as distinct from its reproductive cells.) According to the theory, producing and raising children diverts the body's limited resources away from the task of maintaining and repairing cells, with early aging as the result. The theory has been pretty much confirmed with fruit flies and mice. The data for humans is less conclusive.
Whatever the research shows, parents feel the "disposable soma" in their bones, and every sleepless night minding a colicky baby or waiting up for a tardy teen uses up some of it. We don't need scientists to tell us that enduring a petulant 13-year-old or putting a kid though college takes years off our lives.
But so what? Even if having kids leads us to an early grave, we would still choose to do it. Kids may literally be the death of us, but they are also the best thing in our lives. Especially now, as grandparents, when our children are friends rather than responsibilities, and -- heh, heh -- we get to watch them losing their own disposable cells to the next generation.