1 Applied to behaviour that is not learned (i.e. behaviour that is acquired genetically). In the 1950s and 1960s there was much debate concerning whether particular behaviour is innate or learned; today most ethologists hold that most behaviour has both innate and learned components and studies concentrate on the relative contribution made by each.
2 Applied to behaviour that may be learned but that has evolved by natural selection. In this case, parents behave in a particular way, and teach their offspring to behave likewise, and are more likely for this reason to reproduce successfully. The term is regarded by many ethologists as obsolete because it fails to allow for the modification of patterns of behaviour in response to environmental factors.