Little gray aliens aren't people, no matter how well they fake it. They can be domesticated, though. Might as well keep them around, right?

Homo sapiens domesticus Humans (Homo sapiens domesticus) are short-lived primates of the family Hominidae, and the only existant species of the genus Homo. They originated in Africa, and spread to other continents of planet Earth within a megavorn. While fractious and warlike in their wild state, they are easily trained to a useful function.