For me, the hardest part of writing a story is finding the end. It often feels arbitrary, or artificial, or both. A person’s story isn’t necessarily over, after all, just because I’m ready to write it down. But I can’t put it off forever, either. Editors are waiting, and my unpaid bills. So I squeak out an ending and just cross my fingers that a better one — the real one — doesn’t show itself the day after publication.

Earlier this month, I heard the real ending for a story I wrote more than a year ago about people who use DNA to fill in branches of their family tree. It’s a doozy, and has me thinking hard, again, about