Whatever permutation they chose, though, however they performed the experiment, they found the same thing: what mattered was not the licking-and-grooming habits of the biological mother; it was the licking-and-grooming habits of the rearing mother. When a pup received the comforting experience of licking and grooming as an infant, it grew up to be braver and bolder and better adjusted than a pup who hadn’t, whether or not its biological mother was the one who had done the licking and grooming.
