Claiming behaviors such as kissing the baby provide not only emotional but biological attachment. There is also a very real health benefit for the baby in terms of kissing.  "When a mother kisses her baby, she 'samples' those pathogens that are on the baby's face - the very ones that the baby is about to ingest. These samples are taken up by the mother's secondary lympoid organs like the tonsils, and memory B cells specific for those pathogens are re-stimulated. These B cells then migrate to the mother's breasts where they produce just those antibodies that the baby needs!" (1)