Your cat that cuddles up to you might just as soon hunt you. Genetically speaking, domestic cats have a lot in common with their wild counterparts, according to a study published in the Proceedings of the National Academy of Sciences this week. Where the two differ, says geneticist Wes Warren, an author on the study, is in tameness. Alex Cagan, at Germany’s Max Planck Institute, has also found genetic variation between tame and aggressive rats. Warren and Cagan discuss the possible genetic differences that make certain cats and rats more docile.