Jonathan Zimmerman is a professor of history and education at New York University. He is the author of “Small Wonder: The Little Red Schoolhouse in History and Memory.”

Was Ed Koch gay? I don’t know, and I don’t care. And neither should you.

When the former New York mayor died last week, we heard all the old cliches about why he should have come out of the closet-or why it was necessary to “out” him. If he were openly gay, the story goes, he would have done more to fight AIDS during the early years of the epidemic. And he would have made it easier for other people to come out, too.

But as Koch correctly insisted, his sexual orientation was nobody’s business but his own. And to see why, let’s imagine that Koch wasn't male and gay, but female and straight.

Then let’s suppose that Ms. Koch — like 40% of American women — had undergone an abortion. Would it be OK to “out” her for that, too?...