not kin

“No, Clara was not kin,” he said softly.

“In Plains,” Mrs. Carter added, “everybody that Jimmy’s not kin to, I’m kin to — that’s just about true. It’s just about home. No matter where we go, I’m always ready to go home.”

The varieties on offer at places dedicated to making tortas — called torterías — have also evolved: The "hawaiana" almost always features rings of canned pineapple; the "cubana" is not kin to the Cuban sandwich but rather a local invention of ham, roast pork, headcheese, two types of actual cheese, strips of hot dog, and fried breaded cutlets of beef milanesa, so named for its origins on the Calle República de Cuba in downtown Mexico City.

Biologists have long wondered how such relationships form in the first place and how vampire bats maintain them, especially because the animals involved are not kin.

“Our species is a hyper-cooperative one. No other species is engaged in such a large level of cooperation among individuals who are not kin.”