By JULIA LICHTBLAU

My friend Alison and I have had a running joke that we’re cousins. When we met several years ago, she said, “I bet we’re related. My great-grandmother’s maiden name was Lichtblau.” Her father, like mine, left Vienna in 1938, but she didn’t know much more. Still, we called each other “chère cousine” for fun. Her father, like mine, left Vienna in 1938, and her great-grandmother had the same last name as I do, Lichtblau. Now I’m very fond of Alison, but never seriously believed we were related. The name’s not as rare in Austria as it is here, and I have a family tree going back to my great-great-grandfather—which gets us to 1811, amazingly. (My grandfather, born in 1877, was forty-three when my father came along in 1920, which partly accounts for the long generational leaps.) Alison didn’t know her great-grandmother’s given name, but her married name wasn’t on my tree and had never come up in family reminiscences. Reminiscence is to us Lichtblaus what watching sports on TV is to other families. It’s what we do when we get together. We sit in my aunt and uncle’s Upper West Side apartment on furniture that somehow made it over in 1938 despite looming disaster, and within five minutes, we’re talking about Grandma’s lover. So, I was pretty confident that I’d have heard of Alisons’s great-grandmother if she was one of us.