A man in Wilton, Connecticut named Gary Klahr told a remarkable story in Guideposts a few years back. He said that one night in 1975 he made a new friend at a local restaurant. This new friend, Steve Barbin, happened to be seated at the next table and they got to talking. By the time they finished their burgers, they’d pushed their tables together and were well on the way to becoming best friends. They grew so close that they finished each other’s sentences and shared belly laughs at jokes that no one else seemed to get.

Even the rhythms of their speech seemed identical. They were so close that, at Steve’s wedding, Gary told Steve he was truly his brother. Of course, that was just a figure of speech. Gary said his parents had tried for years to have a child before he came along, and they …