"Twin-Bred" by Karen A. Wyle

The humans on planet Tofarn have ongoing difficulties communicating with and otherwise comprehending the native Tofa...

“Sir? Sir, we have a problem.”

The mayor of Varley looked up from his monitor. “A problem with whom, or with what?”

His assistant considered whether to offer an opinion on whether the Tofa were Who or What, and decided against it. “It’s another complaint from the Tofa, sir. They say that humans are shaking hands.”

“People are trying to shake hands with Tofa? Which hand, I wonder.”

“No, sir. With each other. The Tofa are upset that humans are shaking hands with each other in public. Quite upset.”

“How can you tell? Oh, I know, they vibrate, or smell different, or something. If a job dealing with Tofa has done anything for me, it’s made me appreciate faces, proper ones that tell you what’s behind them. . . .”